If its not already a feature as I can’t find it, I’d like to see an auto tag feature, where if you receive an email from addresses that you specify, it automatically tags it with the tag you want it to.
You can automatically tag specific incoming email messages using a “Local Rule” in eM Client.
There is a basic rule option 5 :-
"Set tag for message from somebody (Not available for IceWarp).
“With keywords: received, from, tag. Click on each keyword to define when (received) a rule is applied, from which senders (from people) and which tag is to be assigned to all such messages”
See eM Client setting up a Rule documentation