Maybe you should consider fixing this issue in FairMail instead? There is no supported way to manage keywords at this moment. Modifying the actual IMAP responses is very hard.

Aki

Am trying... But still there is the issue with the difference of keywords actually used in the mails and the ones in the index file. I had to delete the index files to reset that list - and I don't like deleting the index files on sdbox.

Is there a way to fix or circumvent that?

--
Cheers
spi