Identities let you choose a number of options for how you send mail through your Fastmail account.

They let you control how you appear if you want to send mail through Fastmail on behalf of one of your other external email accounts, as well as from Fastmail itself.

To manage identities:

  1. Open the Settings → Sending Identities screen.
  2. Your list of identities will be displayed under the "Sending Identities" heading. Use the Edit button to edit an identity, or use the blue Add Identity button at the top to create a new one.
  3. Don't forget to Save when you're done.

On this same page, you can set the default identity for your account. New emails will use this identity automatically, unless another one is chosen on the message composition window, or if a default identity is set for the folder from which the message is being composed.

If you add *@domain.tld as an account identity email address with your personal domain, then you will be able to enter something different to replace the * in the From: address bar for each message that you send using this identity.

Identity options

Each identity lets you choose from a number of options:

  • Sending name: The name from which the message will appear as having been sent; e.g., Jonathan. This is what appears in the From: header of the emails you send.
  • Signature: The signature that is added into new messages from this identity. If your default mail format is Rich Text, then your signature will also be in Rich Text, which lets you choose fonts, text sizes, and colors.

Advanced Options

  • Reply To: When a recipient replies to the email, it will go to this address instead of the From: address. Leave this blank unless you want replies to go to a different address.
  • Auto BCC: A Bcc: copy of every email you send from this identity will be sent to the email addresses you specify here. This list can be generated out of your contacts via auto-completion.
  • Also BCC these addresses through 3rd party email clients: If ticked, a Bcc: copy of every email you send via an email client with a From: email address matching this account identity will also be sent to the Auto BCC addresses given above.
  • Save: The folder in which you wish to save a copy of each message you send with this identity. Deselect this option if you don't wish to save a copy of your sent messages.
  • Save a copy when sending through third party clients: If ticked, a copy will also be saved to the Sent folder when you send an email via an email client with a From: email address matching this identity.
  • Nickname: Used to help you tell your identities apart within the Fastmail interface. This is only ever visible to you.
  • Send via (Option only visible if sending mail via a non-Fastmail controlled domain): Normally when you send email, the email will be sent via the Fastmail server. If you are using an identity to send emails from a different service, like your ISP, you can use their server to make sure your emails are delivered properly.
  • Default identity for folders: If you want mail from a folder to use a sending identity by default, you can set this on the the Settings → Folders screen, using advanced preferences. This will put the chosen identity on all mail written from that folder, even if the folder’s default is different than the default for the whole account.

    If you are using a non-Fastmail hosted domain; (e.g.,,, etc.), you may wish to send through the other service's SMTP server, to make sure that your messages are delivered reliably (see the note below on SPF issues).

    • Security: the type of security to use when connecting to the SMTP server.
    • Server: the SMTP server name to send through (e.g.
    • Port: the port to connect to on the SMTP server. Usually 587, or 465 if using "SSL/TLS encrypted" security.
    • Username: the username (normally your email address) to use to log in to the SMTP server.
    • Password: the password to use to log in to the SMTP server.

Extra tips and tricks

If you just want to use an identity for BCC on third party clients or Save a copy on third party clients, you can put a single * as the left side of the email address before the @ to make it match anything. For instance, * will match any email address you send with. If you have an identity with a specific email address already saved, that will take be used first; * matches will only happen if there are no other more specific identities saved.

Identity verification

If you manually create a sending identity that sends through Fastmail's servers, you may see the following error message:

To send as address@domain.tld you must first verify that you own this address.

Clicking Verify will open a new page where you can request a single-use code to verify ownership of the email address that you are trying to send from. Click Send Verification Code. When you have received the verification code at that address, you can then return to this page, enter the code, and click Verify.

Identities that need to be verified will also not be permitted to send through email clients. Attempting to do so will result in the messages getting rejected on the SMTP level.

Identities and SPF

SPF was an attempt to reduce spam by preventing people from forging the domain in the SMTP MAIL FROM envelope of sent email.

SPF has not eliminated spam for a couple of reasons.

  1. Users generally do not see the SMTP MAIL FROM envelope, so it doesn't stop spammers forging the From: header most users see in emails.
  2. Anyone can set up SPF on any domain they own, and SPF doesn't tell you which domains can be trusted.

Whether the SPF checks pass or fail does not usually mean a message is spam or not. We can see this in the SpamAssassin scores, which show that SPF failures by themselves are given a low score:

score SPF_PASS -0.001
score SPF_FAIL 0 0.919 0 0.001 # n=0 n=2
score SPF_NEUTRAL 0 0.652 0 0.779 # n=0 n=2
score SPF_SOFTFAIL 0 0.972 0 0.665 # n=0 n=2

SPF can also break simple forwarding of emails between systems, and requires a separate system called SRS to rewrite the SMTP MAIL FROM envelope to make sure bounces are sent back through the forwarding system to the actual sender of the message.

Despite these problems, some systems treat SPF failures as a sign that the email is likely spam, so you may want to make sure your sent emails pass SPF tests. If you are sending email using your personal domain, you can do this by adding SPF for Fastmail yourself. If you are sending email with a From: address at a domain that is not hosted with Fastmail and doesn't have SPF records authorizing our servers, you should send via that domain's SMTP server instead. This can be done by using the Send messages using an external SMTP server option.

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