FastMail SMTP Configuration
Use these exact values when configuring any email client or application to send through FastMail servers.
| Parameter | Value |
|---|---|
| SMTP Host | smtp.fastmail.com |
| SMTP Port | 587 (TLS) or 465 (SSL) |
| Encryption | STARTTLS on port 587, SSL on port 465 |
| Username | Your full FastMail email address |
| Password | Your FastMail password or an App Password |
Tip: For accounts with two-factor authentication enabled, you must generate an App Password in FastMail settings. Generate one under Settings > Password > App Passwords for use with third-party applications.
Step-by-Step Setup
Follow these steps in order to configure SMTP access for your FastMail account.
1. Enable SMTP Access
FastMail enables SMTP by default for all accounts. Ensure your account is active and in good standing. No additional configuration is typically needed on the server side.
2. Handle Two-Factor Authentication
If you have 2FA enabled, generate an App Password in FastMail settings. Go to Settings > Password > App Passwords and create one labeled for your application.
3. Configure Your Application
Enter smtp.fastmail.com as the SMTP host, port 587 with TLS, your full FastMail email as the username, and your password or App Password as the credential.
4. Send a Test Message
Send an email to yourself and an external address to confirm delivery. Check the FastMail sent folder to verify the message was sent successfully.
Common Errors and Solutions
Most FastMail SMTP issues fall into a handful of categories. Here's how to fix them quickly.
Authentication Failed
If 2FA is enabled, you need an App Password, not your regular password. Generate one in FastMail Settings > Password > App Passwords. If 2FA is off, verify your regular password is correct.
Connection Timeout
Port 587 may be blocked by your network. Try port 465 with SSL encryption as an alternative. Corporate firewalls commonly block direct SMTP on port 587.
Account Suspended
FastMail may suspend accounts for policy violations or payment issues. Check your account email for suspension notices. Restore your account by addressing the underlying issue.
Daily Sending Limit
FastMail has per-day sending limits that vary by plan. Standard accounts typically have lower limits. For production email volume, migrate to a dedicated email infrastructure service.
Best Practices for FastMail SMTP
Keep your account secure and your messages deliverable with these recommended approaches.
Use App Passwords with 2FA
When 2FA is enabled, always use App Passwords for SMTP. Generate unique passwords per application for easier revocation. Keep your main account password separate from application access.
Enable SPF for Custom Domains
If using a custom domain with FastMail, add the appropriate SPF record to your domain's DNS. This improves deliverability and prevents your messages from being flagged as forged.
Use a Custom Domain
FastMail allows custom domains for all plans. Using a custom domain for sending improves your professional image and gives you more control over your email identity.
Monitor Sending Limits
Track your daily sending volume. FastMail has limits that vary by plan. For any meaningful email volume in production, migrate to a dedicated email infrastructure service before hitting limits.
When FastMail SMTP Falls Short
FastMail is a privacy-focused email service, and its SMTP works well for personal and low-volume professional use. However, FastMail wasn't designed for application email sending in production. Strict rate limits, no webhook delivery notifications, and minimal bounce handling make it unsuitable for automated transactional email. A dedicated email API provides the infrastructure and observability that production transactional email requires.
For teams needing reliable transactional email at scale, SMTP relay services handle authentication, IP reputation, and routing automatically. Learn more about email deliverability and why sender reputation matters for inbox placement.
Frequently Asked Questions
What are FastMail's SMTP sending limits?
FastMail limits vary by plan. Standard accounts typically have 100-200 emails per day. Paid plans have higher limits. FastMail focuses on privacy rather than high-volume sending.
Can I use FastMail with a custom domain?
Yes. FastMail supports custom domains on all paid plans. Add your domain in FastMail settings and update your DNS records as instructed. Once verified, you can send from any address on that domain.
My FastMail SMTP is being rejected. What should I do?
Verify you're using an App Password if 2FA is enabled. Check your account isn't suspended. Try switching from port 587 to port 465 with SSL. Verify your username is the full email address.
Is FastMail SMTP suitable for transactional emails?
FastMail is not designed for transactional email in production. It lacks webhook delivery notifications, detailed analytics, and bounce handling. Use a dedicated transactional email service for automated email sending.
How do I generate an App Password in FastMail?
Log in to FastMail and go to Settings > Password > App Passwords. Create a new app password with a descriptive label. Use this password instead of your main password for SMTP.
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