Let Fastmail sort your mail for you. This guide explains the difference between Filters and Rules, then walks you through building your very first rule — no technical know-how required.
Filters vs. rules, and the shape of a rule
A filter is a quick one-off search-and-act; a rule runs automatically on your mail, again and again. Every rule has the same shape: a condition (what to match) and one or more actions (what to do).
Create and apply a rule
Open Filters & Rules
Open the Settings gear, choose Filters & Rules, and click + Create rule.
Set your condition
Pick From (or Subject, To, etc.) and type what to match — then click Continue.
Choose actions
Tick the actions you want — for example Add label and Archive.
Decide what it applies to
Under Apply to…, choose New matching messages on arrival, and tick All matching… now if you also want to sort mail you already have.
Name it and save
Give it a Name, then click Do it (or Save).
“All” vs “Any”. That dropdown at the top matters. All means a message must match every condition; Any means matching just one is enough — handy when one rule should catch many senders.
“Continue to apply other rules.” Leave this ticked if you want your remaining rules to keep checking the message. Fastmail turns it off automatically when an action moves or deletes the message.
Next steps. See Organizing Incoming Mail with Rules and Taming Junk Mail with Rules.