One replaces your whole mailbox. The other keeps your Gmail and
adds custom domain email for $29/yr.
Fastmail is a full paid email host: you migrate your mailbox to Fastmail's own webmail and mobile apps, and it bundles calendar, contacts, and storage starting at roughly $60/yr for the Basic plan with a custom domain included. SendMailAs is not a mailbox - it keeps you inside the free Gmail account you already use and adds custom-domain send and receive for a flat $29/yr covering unlimited domains, with SPF, DKIM, DMARC, and DNS configured automatically through Cloudflare. Honestly, they solve different problems: Fastmail is a complete mailbox replacement with an integrated calendar and contacts for people who want to leave Gmail entirely, while SendMailAs is email-only and deliberately stays in Gmail, so you keep your inbox, filters, and habits and just send as you@yourdomain.com. If you want to switch email providers, choose Fastmail; if you want to keep Gmail and add cheap custom domains, choose SendMailAs.
Fastmail is a hosted mailbox - you move your email into Fastmail's webmail and apps and learn a new interface. SendMailAs keeps your existing Gmail untouched: same inbox, filters, and habits. You just add the ability to send and receive as you@yourdomain.com.
Fastmail Basic is roughly $60/yr and bills per mailbox per month, so costs scale with users. SendMailAs Pro is $29/yr flat with no domain, address, or per-user limits. For the keep-your-Gmail use case, the price gap widens as you add domains or people.
Fastmail walks you through adding MX, SPF TXT, and DKIM records at your registrar for every custom domain. SendMailAs pre-generates the exact records to paste into your existing DNS host and verifies them automatically, for every domain.
Fastmail is a full hosted email service: its own polished webmail and mobile apps, an integrated calendar, contacts, and storage, with no reliance on Gmail or Google at all. SendMailAs is email-only and stays inside Gmail. If you want to leave Gmail entirely and run your whole email stack with one privacy-focused provider, Fastmail is the better fit.
| Feature | SendMailAs$29/yr | Fastmail |
|---|---|---|
| Keeps your existing Gmail | Yes - Keeps your existing Gmail | - |
| Full hosted mailbox | - | Yes - Full hosted mailbox |
| Own webmail + mobile apps | - | Yes - Own webmail + mobile apps |
| Calendar + contacts | - | Yes - Calendar + contacts |
| Send from custom domain | Free | Paid only |
| Receive on custom domain | Free | Paid only |
| Free plan (no trial expiry) | Yes - Free plan (no trial expiry) | - |
| DKIM signing | Auto (your domain) | Manual (your domain) |
| DNS setup | Automatic | Manual (MX, TXT, CNAME) |
| SPF configuration | Automatic | Manual TXT record |
| Domains (paid) | Unlimited | Plan-dependent |
| Addresses (paid) | Unlimited | Per-mailbox pricing |
| Mailbox storage | Uses your Gmail | Included (per plan) |
| Setup time | 5 minutes | Migration required |
Fastmail bills per mailbox. SendMailAs charges once.
| Scenario | SendMailAs | Fastmail |
|---|---|---|
| Custom email, 1 domain (free tier)Fastmail has no permanent free plan | Free | Not available |
| Send + receive, 1 domainFastmail Basic is paid per mailbox | Free | ~$60/yr |
| Send + receive, 5 domainsSendMailAs flat; Fastmail scales per mailbox | $29/yr | ~$60/yr+ |
| Send + receive, 30 domainsSendMailAs has no domain cap | $29/yr | ~$60/yr+ |
| Team mailboxes, 5 usersFastmail bills per mailbox per month | $29/yr | ~$300/yr+ |
Fastmail pricing is approximate and billed per mailbox per month (Basic ~$5/mo). SendMailAs Pro: $29/yr flat. Prices as of May 2026.
Fastmail is an excellent, privacy-focused email host. It has its own well-built apps, an integrated calendar and contacts, and it gives you a complete mailbox independent of Google. If you want to leave Gmail and run your whole email stack with one provider, it's a great choice.
But if you just want you@yourdomain.com working in the Gmail you already use - sending and receiving, with proper DKIM, without migrating or touching DNS records - SendMailAs does that for $29/yr with unlimited domains. Fastmail asks you to move your mailbox and pay per user.
For the keep-your-Gmail use case, SendMailAs is simpler and cheaper. For a full mailbox replacement with calendar and contacts, Fastmail is the more complete product.
No. Fastmail is a paid email host with a 30-day trial but no permanent free plan. The Basic plan is roughly $5/month (~$60/yr) and includes a custom domain. SendMailAs has a free plan that includes both send and receive on 1 domain with 2 addresses, with no trial expiry.
Fastmail is a complete email host - you migrate your mailbox to Fastmail's own webmail and apps, with calendar and contacts included. SendMailAs is email-only and keeps you in your existing free Gmail; it adds custom-domain send and receive without you switching email clients or moving your inbox.
Effectively yes for the full experience. Fastmail hosts your mailbox in its own apps and webmail, so it works best when you move to Fastmail. SendMailAs is built around Gmail - your mail stays in Gmail and you send from your custom domain using Gmail's 'Send mail as'.
Fastmail charges per mailbox per month for full email hosting with storage, calendar, and contacts (~$60/yr Basic and up). SendMailAs is $29/yr flat for unlimited domains because it doesn't host your mailbox - it connects custom domains to the Gmail account you already have.
Fastmail guides you through DNS setup for custom domains and signs outgoing mail with DKIM, but configuration is largely manual at your registrar. SendMailAs pre-generates the exact SPF, DKIM, DMARC, and MX records for you to copy-paste at your existing DNS host, then verifies them automatically - no working out the records yourself.
Fastmail supports custom domains, with limits depending on plan and per-mailbox pricing that grows with more users. SendMailAs Pro is $29/yr for unlimited domains and unlimited addresses with no per-domain or per-user fees.
Fastmail. It's a full productivity suite with calendar, contacts, and its own mobile and web apps. SendMailAs is email-only by design - if you need an integrated calendar and contacts replacement, Fastmail is the better fit.
Choose Fastmail if you want to fully replace your mailbox with a privacy-focused host that has its own apps, calendar, and contacts, and you don't want to rely on Gmail. Choose SendMailAs if you want to keep Gmail and just add custom-domain email cheaply across many domains.
First domain free with send and receive. No credit card.
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