Eric deRuiterJun 24, 2025
If you move a message to your spam folder in #fastmail it may or may not learn that future similar messages are spam—depending on when you created your account. Let me explain. If you go to Settings > Folders > Spam > Show Advanced Preferences you may or may not see the option “Scan this folder daily and learn any new messages as spam.” Older accounts have this option, while newer accounts don’t. @fastmail
Show threadEric deRuiterJun 24, 2025
#fastmail I don’t know what the date is that determines if an account is too new to have the learn as spam option but from looking at multiple accounts is seems to be somewhere in 2010 or 2011.
Show threadEric deRuiterJun 24, 2025

#fastmail their support gives this reasoning:

‘We removed the ability to mark the system Spam folder to "Learn as spam" but allowed users who had this feature already enabled to retain it. The feature was removed because legitimate emails can sometimes get a score high enough to be moved to the Spam folder and we don't want these emails to be "learned as Spam" which will result in an increased number of false positives.’

Show threadEric deRuiter
#fastmail You may set up a folder other than the spam folder to have the ‘learn as spam’ option enabled, but I find this non intuitive. People assume moving a message to their spam folder is training the spam filter, and will not even realize they should be creating a different folder specifically to move spam to.
Jun 24, 2025 at 10:41pmIvory for iOS
Show threadEric deRuiterJun 24, 2025

#fastmail Using the “report spam” button from the web or app interface should be putting the message in spam and training, but doing a regular move in the web interface, the app, or in a mail client such as Apple Mail will not cause the spam folder to lean unless the account is old enough and the learn option is still enabled.

If you are using a mail client such as Apple Mail you don’t have access to the report spam button so creating the custom learning folder is your only option.

Show threadEric deRuiterJun 24, 2025
#fastmail I have been trying to get more clarification from Fastmail support about this as well as how moving a message out of spam to learn that it is not spam is possibly affected by the learn option. I have observed accounts without the learn option that don’t increase their count of learned messages even when using the ‘report spam’ or ‘not spam’ buttons. I’m talking a decade old high volume account with only a couple dozen messages learned.
Show threadEric deRuiterJun 24, 2025
#fastmail What Fastmail support have told me has contradicted other info in the same support thread. I’m waiting on tier 3 and will update this thread when I know more.
Show threadEric deRuiterJun 28, 2025
#fastmail It seems that a compromise solution between not having the learn option on the spam folder and learning everything is that they could identify which messages the filter puts in spam and have the learning rule ignore them, which leaves it free to learn from just those messages that were added manually.