[horde] Empty content of folder at login (login tasks)

[Louis-Philippe Allard]

Hello,  I would like to create a rule or filter to totally empty (delete)
the contents of a SPAM folder at login time in Horde.  I have looked under
filters where I already have created several filters to sort emails
according to their senders, but nowhere I could find a way to tell horde to
empty the contents of a specific folder.  There must be a way to do so,
and I would appreciate if someone could point it out to me.  More
generally, how does Horde (Imp) treats spam emails?  I use Gmail as my
relay so I cannot use spamassasin or anything similar.  Gmail already tags
the spam as such, and moves them to the "Spam" folder.

Lately on gmail the amount of spam has increased by a 2-3x and its not rare
that I have to manually delete 40-60 emails per day.

Thanks