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Fastmail Setup

1

Open Fastmail Security settings

Log in to Fastmail and go to Settings → Privacy & Security → App Passwords.
2

Create an app password

Click New app password.Name it: Claude Email ConnectorFastmail generates a 32-character password. Copy the full string.
3

Provide credentials to Claude

FieldValue
Emailyour-email@fastmail.com
Password32-char app password
IMAP Serverimap.fastmail.com
SMTP Serversmtp.fastmail.com
Port993 (SSL)
Fastmail lets you create a separate app password for each client. To revoke Claude’s access later, just delete that specific password — your other apps won’t be affected.

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Troubleshooting

Fastmail app passwords are 32 characters (not 16 like Apple or Microsoft). This is normal. Copy the full string including any special characters.
Custom domain addresses work the same way. Use your custom domain email address (e.g., you@yourdomain.com) as the login email, and generate the app password from your Fastmail account settings as normal.