Mail Hosting Guide 2026: Corporate Email Hosting, Pricing and Configuration

For a corporate brand, mail hosting is not just another technical service in the communications stack; it is the backbone through which contracts, invoices, customer data and operational workflows flow every single day. A company that bills clients from info@gmail.com erodes trust the moment that first email lands, while a properly configured info@yourcompany.com mailbox directly influences brand recognition, deliverability and even corporate SEO signals. This guide covers mail hosting end to end — from protocol fundamentals to purchasing criteria, from pricing tiers to SPF/DKIM/DMARC configuration.

Related guides: Corporate email address setup guide · What is web hosting, types and how to choose · What is DNS and how to change settings · cPanel website management · Plesk panel management · Free SSL with Let's Encrypt

What Is Mail Hosting and How Does It Differ From Web Hosting?

Mail hosting (also called email hosting, e-mail hosting) is a dedicated server infrastructure where email accounts tied to a domain are stored, transmitted and managed. Web hosting plans typically include an email feature, but there email runs as a side service on shared resources — sending limits are tight, IP reputation is weak and storage is carved out of your disk quota. Mail hosting, by contrast, is a service optimized exclusively for email, running on separate IP pools with dedicated antispam infrastructure.

The practical difference is easy to see: a typical shared hosting plan caps you at 100-300 messages per hour, while a professional mail hosting solution operates in the 5,000-50,000 messages-per-hour range, delivers through a dedicated SMTP relay and continuously monitors sender reputation. Email bundled with a web hosting plan is a side feature; corporate mail hosting is a first-class product.

The core components of a mail hosting system are:

• MTA (Mail Transfer Agent): Postfix, Exim, Sendmail or Microsoft Exchange — handles server-to-server message delivery.
• MDA (Mail Delivery Agent): Dovecot, Courier — writes the message into the user's mailbox.
• MSA (Mail Submission Agent): Receives client submissions, typically over port 587.
• Webmail: Roundcube, SOGo, RainLoop, Horde — the browser-based interface.
• Antispam layer: SpamAssassin, Rspamd, ClamAV antivirus scanning.
• Authentication: SPF, DKIM, DMARC records and client-side SASL/STARTTLS verification.

Why Corporate Mail Hosting Instead of Free Gmail / Hotmail?

yourcompany@gmail.com may look acceptable for a hobby site, but for a business that issues invoices, signs contracts and runs e-commerce it creates serious problems. First, brand perception: when your customer sees an email that doesn't come from your own domain, they immediately question your professionalism. Second, regulatory compliance: under GDPR (and Turkey's KVKK) you may unwittingly transfer customer data to third countries. Third, control: if your account gets locked, you'll be waiting for Google Support to respond — whereas with your own mail hosting, IMAP backups, alias management and data portability are entirely in your hands.

The email hosting decision isn't merely cosmetic; in our corporate email address setup guide we covered the seven most common mistakes businesses make in detail. The list below is short but pointed.

• Brand trust: A domain-based address signals 'corporate structure' to customers; a Gmail.com address looks like a one-person freelancer.
• Data ownership: With mail hosting, the mailbox is yours — the server is yours, or stored under your contract.
• SPF/DKIM/DMARC control: You can fully manage sending policies only on a mail hosting tied to your own domain.
• Account flexibility: Role-based mailboxes like sales@, support@, billing@ and unlimited alias creation.
• Backup & archiving: Mail hosting plans offer daily automatic backups and 7-365 day point-in-time recovery.

Mail Hosting Types: Shared, Dedicated, Cloud and Self-Hosted

Mail hosting isn't a single product; it splits into four main architectures. Picking the wrong one significantly affects both price and deliverability. Our general hosting types article explains the same logic on the web server side.

• Shared mail hosting: Mailboxes for hundreds of different domains live on the same server. Lowest cost (around $1-5 USD/month), enough for small offices with 5-25 accounts. Downside is the 'noisy neighbor' effect — if another domain on the server starts spamming, the entire IP gets blocked.
• Dedicated mail hosting: A single-customer server with dedicated IP and dedicated resources. Around 5% of SMBs need this tier; pricing ranges roughly $50-250 USD/month. Preferred in high-volume, high-sensitivity sectors like banking, insurance and healthcare.
• Cloud / Hosted mail (SaaS): Microsoft 365 Exchange Online and Google Workspace are the best-known examples. Scalability is unlimited; per-user license fees add up over time. Enterprises typically keep admin accounts on SaaS and production workloads on local mail hosting — a hybrid approach is common.
• Self-hosted (on your own server): With Postfix + Dovecot + Rspamd on a $5-15 USD/month VPS you can create unlimited accounts; however, DNS, IP reputation, blacklist monitoring, antispam tuning, backups and uptime are all on your shoulders. Read our VPS guide and Linux server administration basics article.

Protocols: IMAP, POP3, SMTP, MAPI, ActiveSync

The most technical part of the mail hosting decision is protocol compatibility. Without the right port + right encryption + right authentication trio, users will end up staring at 'certificate error' or 'authentication failed' warnings on their client screens.

• IMAP (143/993): Messages stay on the server — the modern standard for multi-device sync. Use port 993 with SSL/TLS.
• POP3 (110/995): Messages are downloaded and (by default) deleted from the server. A historical choice for users on a single device.
• SMTP (25/465/587): 25 is for server-to-server, 587 is client submission with STARTTLS, 465 is implicit-TLS submission.
• MAPI: Microsoft Exchange's proprietary protocol — rich Outlook integration (calendar, contacts, GAL).
• EAS / ActiveSync: Microsoft-licensed protocol for push email + calendar + contacts sync on iOS / Android.
• CalDAV / CardDAV: Open standards for calendar and contacts sync — works with SOGo, Nextcloud and similar.
• JMAP: The modern successor to IMAP, RFC 8620; not yet widespread but growing under Fastmail's leadership.

The table below shows the standard port + encryption combinations:

Never use port 25 on the client side — 95% of ISPs block this port on end-user IP ranges. For submission, 587 (STARTTLS) or 465 (TLS) is mandatory. RFC 6409 has defined this distinction since 1998.

DNS Records: MX, A, PTR and SRV

DNS is where the mail delivery chain begins. A wrong MX record, a missing PTR (rDNS) or a faulty SPF is the direct cause of your mail landing in the spam folder. If you already know the basics from our DNS guide, you'll set this up quickly.

PTR (Reverse DNS) is mandatory: the sender IP must resolve back to your domain in reverse, otherwise mail you send to Gmail / Outlook goes straight to spam. You don't set up PTR in your own DNS — you request it from the panel of the ISP / hosting provider that issued the IP.

SPF, DKIM, DMARC: The Three Pillars of Deliverability

In 2026, no serious mail hosting setup is considered complete without these three records. Since February 2024, Google and Yahoo have required DMARC for any bulk sender. For details, refer to Google's official sender guidelines.

SPF (Sender Policy Framework) — RFC 7208. A TXT record published in DNS that declares which servers are authorized to send mail on behalf of your domain. There must be exactly one SPF record, and it must not exceed the 10-DNS-lookup limit.

~all means softfail (mark as suspect), -all means hardfail (reject). In production, use ~all until SPF matures; switch to -all after monitoring is complete.

DKIM (DomainKeys Identified Mail) — RFC 6376. The server cryptographically signs every outgoing message with a private key; the receiver verifies the signature with the public key published in DNS. 2048-bit RSA is standard.

DMARC (Domain-based Message Authentication) — RFC 7489. The policy that tells receivers what to do when SPF or DKIM fails, and that kicks off the reporting flow. p=none means monitor only, p=quarantine means send to spam, p=reject means reject outright.

DMARC reports arrive daily as XML and are hard to read manually. Use dmarcian.com, Postmark DMARC Digests, or the self-hostable parsedmarc to visualize the reports.

The new sender standards of 2026: BIMI and MTA-STS. BIMI (Brand Indicators for Message Identification) — to display your brand logo next to the sender name in Gmail and Yahoo, you need a DNS record + SVG logo + VMC certificate combo. DMARC at p=quarantine or p=reject is required.

MTA-STS (RFC 8461) forces other MTAs sending to your domain to use TLS encryption. It consists of a web-served policy file (mta-sts.txt) and two TXT records:

Webmail host choice: 'Webmail' refers to the PHP/JS interface that lets users access their email from a browser. Almost every mail hosting provider ships one out of the box; on self-hosted setups you pick your own. Common options: Roundcube (most common, large plugin ecosystem, the default in cPanel and Plesk), SOGo (groupware-focused with ActiveSync + CalDAV + CardDAV), RainLoop / SnappyMail (ultra-lightweight, single-file install), Mailpile (personal use, GnuPG integration), Modoboa (Python/Django-based with an admin panel).

Mail Hosting Pricing Tiers (2026)

Anyone searching for mail hosting prices really wants a clear answer to 'how many users, how many GB, how much?'. The figures below are 2026 industry averages drawn from SERP analysis; they vary by provider and exclude tax. When hunting for the cheapest email hosting, beware: anything sold under $1/month with an 'unlimited' claim usually has tight hourly send limits, low storage quotas and poor IP reputation. Before signing, use our domain lookup tools to check the provider's history.

• Mini plan (1 account, 1-5 GB): around $1-3 USD/month — small freelance use, single mailbox.
• Starter plan (5 accounts, 5-10 GB/account): around $3-9 USD/month — small office, boutique agency.
• Professional plan (10-25 accounts, 10-25 GB/account): around $9-30 USD/month — SMB, branch office.
• Business plan (25-100 accounts, 25-50 GB/account): around $30-120 USD/month — mid-size company, multiple departments.
• Enterprise / dedicated (unlimited accounts, dedicated IP): around $120-500 USD/month — large enterprise, dedicated SMTP relay.
• Microsoft 365 Business Standard: ~$12-15 USD/user/month (Exchange + Office + 1TB OneDrive).
• Google Workspace Business Standard: ~$12 USD/user/month (Gmail + 2TB Drive + Meet).

Provider Comparison: Local and Global Players

Taking a vendor-neutral view, the most commonly seen mail hosting providers globally include Hostinger, Zoho Mail, Fastmail, Microsoft Exchange Online, Google Workspace, Rackspace Email and IONOS, while regional providers serve country-specific markets (for example Natro, Doruk Net, Hosting.com.tr in Turkey). Comparison criteria: data location (regional providers can offer in-country data centers — critical for GDPR / KVKK), billing cadence (most regional providers charge annually upfront, while SaaS competitors bill monthly), Outlook / Exchange compatibility (some local providers offer MAPI/EWS support as an optional extra), first-year discount vs. renewal pricing (50-70% first-year discounts are common, with year two renewing at list price), migration assistance (prefer providers that offer IMAP-to-IMAP migration), SLA and technical support (99.9%+ uptime SLA and 24/7 phone support should be standard).

Self-Hosted Mail Server with Postfix + Dovecot

For those wanting to run their own corporate mail server, the Postfix + Dovecot + Rspamd trio on Linux is the industry standard. Below is an outline of a from-scratch install on Ubuntu 24.04 LTS. We recommend reading our Linux server administration basics guide first. The learning curve for manual Postfix configuration is steep; ready-made docker-compose-based solutions (Mailcow Dockerized, Mail-in-a-Box, Modoboa, Poste.io, iRedMail) shoulder most of that load.

To make the setup above production-ready you'll need Rspamd config tuning, fail2ban rules and regular backups. Our fail2ban guide applies the same approach to SMTP/IMAP brute force. Mailcow is the most popular ready-made package:

For more on Docker, see our Docker Compose guide and deploying applications with Docker article.

Client Configuration: Outlook, Apple Mail, Thunderbird, Mobile

Once the mail hosting provider has provisioned your plan, the client side comes next. Serving autodiscover.xml and autoconfig.xml instead of relying on manual setup dramatically improves the user experience. On iOS / Android, prefer plans that support Exchange ActiveSync (EAS) — push email, calendar and contacts sync all run through a single account. On the open source side, SOGo provides this support.

Antispam and Antivirus: Rspamd, SpamAssassin, ClamAV

Spam landing in the inbox costs the user time; legitimate mail that fails to deliver costs the business revenue. You need to tune both directions: inbound (filtering) and outbound (sender reputation). Common components: Rspamd (modern, fast, Lua-based rule system — the preferred replacement for SpamAssassin), SpamAssassin (the classic, perl-based, still widely deployed), ClamAV (open source antivirus, scans mail attachments), amavisd-new (a content filter that bridges SpamAssassin + ClamAV into Postfix), DNSBL / RBL (real-time blacklists like Spamhaus, SORBS, Barracuda), greylisting (temporarily rejects the first attempt, real MTAs retry).

Backup, Archiving and Compliance

The mailbox is corporate memory; accidentally deleting one account can wipe out months of project history. Backup strategy should follow the 3-2-1 rule: at least 3 copies, on 2 different media, with 1 stored off-site. For compliance: where do you store user data? Where do backups go? When an employee leaves, how many days until the mailbox is deleted? Your company should have a written policy answering these three questions. EU-based providers attach GDPR clauses to their contracts; Turkey-based mail hosting providers do the same with KVKK terms.

Email Encryption: TLS, S/MIME and PGP

When server-to-server transfer is encrypted with TLS, you have transit security; but the message remains readable in the sender's mailbox. For end-to-end encryption you have several options: STARTTLS / TLS server-to-server encryption (can be enforced via MTA-STS); S/MIME native in Outlook/Apple Mail/Thunderbird, requires a CA-signed certificate; OpenPGP native in Thunderbird, Gpg4win for Outlook, key management on the user; Autocrypt automatic key distribution via mail headers; ProtonMail / Tutanota native E2E mail hosting alternatives.

Mail Hosting Performance Tuning

In high-volume corporate use, mail server bottlenecks usually surface in disk I/O and the antispam pipeline. Practical recommendations: use Maildir format (not mbox) — parallel reads/writes are much faster; pick NVMe disks — Maildir produces millions of small files; keep Dovecot index files on a separate SSD partition; run antispam as a milter — pre-queue (before-queue) rejection saves bandwidth; use connection pooling with service_count = 0 to reuse imap-login processes; apply submission rate limits to cap the hourly message count per user (preventing a compromised account from becoming a spam cannon).

Mail Hosting Migration: From Old Provider to New

Migrating from one mail hosting to another isn't a casual task once you factor in storage, alias structures, user passwords and ongoing conversations. Here's an 8-step sequence aimed at zero data loss:

• 1. Inventory: List every account, alias, forwarder and quota usage.
• 2. Create accounts on the new provider: Same addresses, temporary passwords.
• 3. Start IMAP-to-IMAP sync: Use imapsync or offlineimap to copy existing mailboxes to the new server.
• 4. Lower DNS TTL: Drop the MX record TTL to 300 seconds (24 hours in advance).
• 5. MX cutover: Point to the new server; keep relay on the old server for 7 days to catch trailing mail.
• 6. Delta sync: Run incremental syncs for 7 days post-cutover to capture any straggler messages.
• 7. Update SPF/DKIM/DMARC: Add the new provider's includes to DNS.
• 8. Archive the old mailbox: Keep read access for 30-90 days; take a final backup, then delete.

Sender Reputation, Blacklist Removal and Warm-Up

Sending 10,000 emails on day one from a freshly assigned IP will land that IP on Spamhaus, Barracuda and Microsoft SNDS lists almost instantly. IP warm-up needs to ramp gradually: Days 1-3 50-100 emails/day (to your most engaged recipients), Days 4-7 200-500/day, Weeks 2-3 1,000-3,000/day, Week 4+ 5,000-10,000/day; reaching the 1,000,000 scale takes 6-12 weeks. Check whether you've been blacklisted weekly with mxtoolbox.com/blacklists. Removal procedures vary by list; most accept a one-click request, but if you re-list, the cooldown jumps to 30+ days.

Compliance: GDPR, KVKK, HIPAA and Sector-Specific Obligations

Because mailboxes contain customer data, they fall directly under data protection regulations: GDPR in the EU, KVKK in Turkey, and sector-specific frameworks in the US such as HIPAA (health), GLBA (finance) and FERPA (education). Compliance checklist: data location (EU/Turkey-based data centers for those customer bases), data retention period (how many days after an employee leaves is the mailbox deleted?), breach notification (within 72 hours to the relevant authority), access logs (6-12 month log retention, audit trail, IP-based login records), multi-factor authentication (2FA) (TOTP, FIDO2 or SMS), data portability (if the customer requests, you must be able to export the mailbox in standard formats — mbox/eml).

Outlook & Exchange Online hybrid approach: some companies keep executive accounts on Microsoft 365 Exchange Online and production/operations teams on local mail hosting. Both sides appear in the SPF record, and DKIM is signed independently from each.

Common Mail Hosting Mistakes

• Exceeding the 10-DNS-lookup limit in SPF: Adding too many includes produces an invalid SPF. Validate with kitterman.com.
• Leaving DKIM at 1024-bit: Modern providers consider 1024-bit weak; use 2048-bit.
• Jumping straight to DMARC hardfail: Move through p=none, p=quarantine, p=reject in sequence.
• Missing PTR record: Two-way alignment between sender hostname and IP is mandatory; otherwise Gmail/Outlook will spam-bin you.
• Using port 25 on the client: 587 or 465 are required; 25 is server-to-server only.
• Using wildcard MX: Set explicit MX records for sub-domains; wildcard MX is an open invitation to spam.
• Not enabling 2FA on webmail: A single compromised account turns your brand reputation into a spam engine.
• Old TLS protocols: TLSv1.0/1.1 must be disabled; SSLv2/v3 should already be off.
• MX changes without low TTL: If you don't drop TTL 24 hours before cutover, you'll hit nasty surprises.
• Untested backups: A backup whose restore procedure has never been tested = no backup at all.

Corporate Mail Hosting Selection Checklist

An 18-item checklist to run past the provider before signing the contract:

• Where is the data center? Is GDPR/KVKK compliance written into the contract?
• What is the per-mailbox storage quota, and is it expandable?
• What is the hourly / daily send limit?
• Are SPF/DKIM/DMARC configured automatically, or manually?
• Is 2048-bit DKIM supported?
• Are ActiveSync and MAPI supported alongside IMAP/POP3/SMTP?
• What webmail option is offered (Roundcube, SOGo, RainLoop)?
• Is 2FA supported (TOTP, FIDO2)?
• Are antispam / antivirus included or extra?
• Are greylisting, DNSBL and content filtering active?
• What is the backup frequency and retention period?
• Is IMAP-to-IMAP migration service included?
• What is the SLA uptime guarantee (99.9% minimum)?
• Is technical support 24/7 phone + ticket?
• Is billing monthly or annual upfront? What's the renewal price hike policy?
• Is the data export procedure clear when transferring the domain out?
• Are catch-all, alias, forwarder, autoresponder included?
• Can user logs be exported (for compliance purposes)?

Don't Confuse With Email Marketing: Transactional vs Marketing

Your mail hosting plan is for daily correspondence; for high-volume newsletters, campaigns or transactional traffic, use a separate SMTP relay service (Amazon SES, Mailgun, SendGrid, Postmark and similar). Mixing manual mail with a 50,000-recipient campaign on the same IP pool will trash your IP reputation. Cleanly separate the three layers: transactional SMTP (one-off triggered emails like password resets, order confirmations, billing statements), marketing ESP (newsletters, campaigns, segmentation, open reports, click tracking, suppression list management), mail hosting (person-to-person daily correspondence).

Monitoring and Alerting: Server Uptime and Mail Flow

Learning that your mail hosting is down from a customer is reputation-shattering. Our Prometheus + Grafana server monitoring guide covers the same territory. Signals to monitor: port checks (TCP handshake to ports 25/465/587/993 every minute), SMTP HELO test (send a test email every 5 minutes and verify the queue clears), queue size alerts (alarm if Postfix queue exceeds 1000 messages), disk usage (warn if /var/vmail goes above 85%; new mail may be rejected at 95%), SSL expiry (alert 14 days out; 30 days for Let's Encrypt), DNSBL listing (hourly check whether your IP is on Spamhaus / Barracuda).

The Future of Email: JMAP, AI Assistants and Federated Mail

Email is over 50 years old, yet still evolving. JMAP (RFC 8620) aims to replace IMAP with a modern HTTP/JSON-based API; on mobile, the battery and speed advantages are clear. On the AI side, LLM-powered features like Gmail's smart compose suggestions and summarization assistants are quickly making their way into corporate mail. Federated mail is still alive: direct MTA-to-MTA communication is possible, but as large providers raise the reputation bar, life gets harder for small self-hosted servers. The richer ecosystem around packages like Mailcow is the developer community's response to this trend.

Diagnostic commands — troubleshooting cheatsheet:

Mail Hosting Cost Comparison Study

A 3-year total cost of ownership (TCO) example for a 15-user SMB:

• Free Gmail (no custom address): $0 — but brand loss, compliance risk, ad exposure.
• Local shared mail hosting (15 accounts, 10GB/account): ~$120 USD/year × 3 = $360 USD.
• Local corporate mail hosting (15 accounts, 25GB/account, ActiveSync): ~$240 USD/year × 3 = $720 USD.
• Microsoft 365 Business Standard (15 licenses): 15 × $12 USD × 36 months ≈ $6,480 USD.
• Google Workspace Business Standard (15 licenses): similar, ≈ $6,480 USD.
• Self-hosted Mailcow on VPS (8GB RAM): VPS ~$170 USD/year × 3 + 80 sysadmin hours/year ≈ $2,800 USD.
• Conclusion: For an SMB, local mail hosting + a separate transactional ESP is the cheapest path. If the team also needs an Office suite, Microsoft 365 starts to make sense. For 50+ users, a hybrid approach yields the best result.

Frequently Asked Questions

How long does it take for mail hosting to go live? Once payment is confirmed, the plan activates in minutes. DNS changes (MX, SPF, DKIM, DMARC) propagate in 1-24 hours depending on TTL. For a fast cutover, drop the TTL to 300 seconds in advance.

Can I use mail hosting and web hosting on the same domain? Yes — the MX record and the A record are independent. Your website can sit behind Cloudflare while your mail runs on a separate mail hosting provider.

What can I do if I lose my mail account? It depends on the provider's backup retention (usually 7-30 day recovery). Archive critical mailboxes weekly to your own side with imapsync or mbsync.

I'm landing in spam, what should I do? In order: validate SPF/DKIM/DMARC, check the PTR record, scan the IP against blacklists, run an IP warm-up, reduce spam-trigger words, send HTML/text alternatives.

What happens if my mailbox quota fills up? Incoming mail bounces or queues. Configure quota warnings to fire at 85%; set up an automatic archive policy. Upgrading account count takes seconds; switching providers requires a migration cycle.

How do calendar / contacts sync work in Outlook and Apple Mail? Outlook uses MAPI/EWS or ActiveSync; Apple Mail uses CalDAV/CardDAV. Not every provider supports all of these — verify before purchasing.

Alternative Approach: Privacy-First Mail (E2E)

For small teams that need maximum privacy, there are E2E (end-to-end) encrypted mail hosting alternatives. ProtonMail (Switzerland), Tutanota (Germany), StartMail (Netherlands) and Mailfence (Belgium) are the best-known names in this category. Custom domain support arrives at the higher tiers; budget around $5-12 USD/user/month. The trade-off in this category: you're limited to the webmail browser app or forced to use a vendor-specific client (standard Outlook integration usually requires a bridge utility).

Related Tools and Articles

• DNS Lookup Tool — verify your MX, SPF, DKIM and DMARC records in a single click.
• SSL Check Tool — test the validity of your mail server's SSL certificate.
• Corporate Email Address Setup Guide
• What Is DNS and How to Change Settings
• Free SSL with Let's Encrypt
• Brute Force Protection with Fail2ban
• Database Backup Strategies
• Monitoring with Prometheus + Grafana

Every team has its own optimal mail hosting choice. Use the quick decision matrix below as a reference:

• 1-3 person freelance / start-up: Mini plan (1-5 accounts, 1-10GB/account), around $1-3 USD/month.
• 5-15 person small office: Starter plan, plus Mailgun/SES for transactional.
• 15-50 person SMB: Professional plan + ActiveSync, optionally hybrid with Microsoft 365.
• 50-200 person company: Business plan + dedicated IP + archiving; benchmark against Microsoft 365 / Google Workspace.
• 200+ person enterprise: Dedicated server + dedicated SMTP relay + on-prem Exchange / hosted Exchange Online; SLA 99.95%+ required.
• With a dedicated tech team: Self-hosted Mailcow + multi-region failover.

Conclusion: The Right Mail Hosting Is an Investment, Not a Cost

The mail hosting decision is a strategic one with direct impact on brand perception, customer trust, regulatory compliance and operational efficiency. Instead of chasing the lowest price, make deliverability (SPF/DKIM/DMARC), uptime SLA, regulatory compliance, backup retention and support quality your primary decision metrics. A properly built and properly monitored mail hosting setup returns hundreds of times its few-dollar-per-user-per-month cost. After reading this guide, the first three steps to take: (1) check your domain's current SPF/DKIM/DMARC status with the DNS Lookup tool; (2) ask the 18 checklist questions of two candidate providers; (3) start your migration plan 4 weeks ahead.