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:

Advanced Options

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.

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.