IMAP
| Server | imap.fastmail.com |
| Port | 993 |
| SSL/TLS Encryption | Enabled, but not STARTTLS |
| Username | Your full email address |
| Password | Your app-specific password |
| Root folder/IMAP path prefix | (leave blank) |
| Folder separator | / (forward slash) |
Do not enable secure password authentication (SPA). It is not needed when you use SSL/TLS encryption and it will not work.
POP
| Server | pop.fastmail.com |
| Port | 995 |
| SSL/TLS Encryption | Enabled, but not STARTTLS |
| Username | Your full email address |
| Password | Your app-specific password |
SMTP
| Server | smtp.fastmail.com |
| Port | 465 |
| SSL/TLS Encryption | Enabled, but not STARTTLS |
| Authentication | PLAIN |
| Username | Your full email address |
| Password | Your app-specific password |
If your client supports STARTTLS only, you can use port 587 with STARTTLS enabled.