Personalities allow you to specify a bunch of options for how you send mail through your FastMail account. To manage personalities:

  1. Open the Advanced → Personalities screen.
  2. Your personalities will appear in the sidebar. Click one to edit its details. When you are done editing, click the Save personality button at the top or the bottom of the page to update your personality.

Personality options

Each personality has a number of options associated with it:

Extra tips and tricks.

If you just want to use a personality for BCC on SMTP or Sent Items on SMTP, you can put a * in the email address on either side of the @ to make it match anything. For instance, * will match any email address you send with. If you have a personality with a specific email address that matches a From address, that will take precedence; * matches will only occur as a fallback.

For use within the web interface, it's not meaningful to use personalities which have a * in the domain part: you'll probably just end up with a bounced email.

Personalities and SPF

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

Unfortunately SPF has not reduced spam at all because: a) no user ever sees the SMTP MAIL FROM envelope, so it doesn't stop spammers forging the From header users see in emails, and b) anyone can setup SPF on any domain they own, and SPF doesn't tell you which domains to actually trust.

Whether the SPF checks pass or fail has little correlation with whether a message is spam or not. We can see this in the SpamAssassin scores, which show that SPF failures have quite 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

Additionally, SPF breaks the simple forwarding of emails between systems, and requires a separate system called SRS to rewrite the SMTP MAIL FROM envelope and to forward bounces back through the forwarding system.

Despite that, some systems treat SPF failures as a sign of spaminess, so you may want to make sure your sent emails pass SPF tests. If you are sending email with a From address from a domain that's not hosted with FastMail and doesn't have specific SPF records authorising our servers, you should send via that domain's SMTP server instead, using the External SMTP server option.