pb with pop_last

[KP Kirchdoerfer <kapeka@xxxxxxxxxxxxxxxx>]

Hi;

I'm new to the list and new to mutt.

After reading a lot of documentation and googling I still cannot resolve the 
problem that "set pop_last" does not seem to work. I understood that "set 
pop_last=yes" prevents my mailer to download teh same mails from a popserver 
every time I fetch it. 

I doublechecked with the same account from another machine with kmail that the 
mailservice provider isn't the culprit.

I tried setting
set pop_last
set pop_last=yes
in .muttrc, but without success.

I do not use fetchmail, instead I use the fetch options of mutt.
mutt version is 1.5.17; ubuntu package.

Any hints?
TIA
kp