I would do this: Tools > Message filters make sure 'Filters for' is for the correct account click on 'New'

give Filter a suitable name Apply filter when: Select: Manually run' Select: 'Getting new mail'

If you want your Junk filters to run first to rmove potential Junk and stop your filter filtering possible junk: Select: Filter after Junk classification'

If you want to run this filter to include potential Junk and/or move the emails before Junk thinks it is junk: Select: 'Filter before Junk Classification'

If setting one condition or you need all conditions to be true: Select; 'Match all of the following'

If setting more than one condition, but any of those conditions can be true: Select; 'Match any of the following'

So if trying one condition - Match all of the following option 'Subject' and 'contains' and type: GG then set the Action eg: 'Move Message to' and select the folder on the account click on OK.

This should only filter messages with GG anywhere in the Subject, but if those messages also have GG in both subject and content then they will still be filtered because it was in the Subject.

Thank you Toad-Hall for taking the time to respond to my question. But you have only explained (very clearly) how to set up an ordinary filter. I know how to do that, but my problem is more complicated. I need to find the "exactly this" condition. In my actual case, I want to filter for GG, as though it were a word with no other letters. When I set up a filter for GG, I also get words which have those letters within them, like "logged" and "baggage". Is there a way to filter for spaces, as in "(space)GG(space)"?

Thanks again for your time.

I think FiltaQuilla might be useful. It adds so-called Regular Expressions to the filter system, where you could use a construction like:

"subject regex" "matches" "/\bgg\b/i"

\b means a word boundary gg is your two letters \b is the trailing word boundary

/ and /i mean ignore the case, so it'll find gg, GG, Gg and gG.

There lots of ways of doing this. You could have

[ ]GG[ ]

where it would require a space (explicitly; nothing else!) before and after, and capital letters. \b is usually superior as it matches at the beginning and end of the line, and recognizes regular punctuation in addition to spaces.