Fastmail SMTP settings: smtp.fastmail.com, port 465/587, app password
Fastmail outgoing server: smtp.fastmail.com, port 465 SSL (or 587 STARTTLS), full address and an app password with SMTP access. Per-plan limits and identity rules.
Fastmail outgoing mail server:
smtp.fastmail.com, port <code>465</code> (SSL/TLS) or <code>587</code> (STARTTLS), username = your full Fastmail address (any address on your account), password = an app password created with "SMTP".
Fastmail SMTP settings at a glance
| Outgoing (SMTP) host | smtp.fastmail.com |
|---|---|
| Ports & encryption |
465 — SSL/TLS <em>(recommended)</em>587 — STARTTLS |
| Username | your full Fastmail address (any address on your account) |
| Password | an app password created with "SMTP" (or "Mail") access — Fastmail refuses the main password from third-party apps |
| Authentication | Settings → Privacy & Security → Integrations → App passwords → New app password → choose access "Mail (IMAP/POP/SMTP)" or "SMTP only". |
How to set up Fastmail SMTP
- Create an app password with SMTP access.
- App settings: host smtp.fastmail.com, port 465, SSL/TLS, username = full address, password = app password.
Sending limits
- Daily/hourly limits depend on the plan and account age; Fastmail publishes them in its help pages and raises them for established accounts.
- From must be an identity/alias configured on the account, or a domain hosted at Fastmail.
Things that catch people out
- SMTP-only app passwords cannot read mail — good for servers.
Common Fastmail SMTP errors
| Server reply | Meaning | Fix |
|---|---|---|
535 5.7.8 Authentication failed | Main password used or app password lacks SMTP access. | Create an app password with SMTP access. |
553 5.7.1 Sender address rejected: not owned by user | From address is not an identity on the account. | Add the identity or send from an existing one. |
More codes: 535 authentication failed, 550 relay denied, 554 rejected as spam, connection timed out — or all SMTP error codes.
When Fastmail is not enough for your app
When a provider caps you or blocks a port, point the same app at QueenSMTP instead: host smtp.queensmtp.com, port 587 (STARTTLS) or 465 (SSL), your SMTP username and password from the dashboard. $5/year plus $0.10 per 1,000 emails, 100 free a day to test.
Get SMTP credentials — free to test Test Fastmail nowRelated settings
Fastmail SMTP — questions
smtp.fastmail.com on port 465 (SSL) or 587 (STARTTLS), with your full address and an app password that has SMTP access.
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