On Tuesday,  1 May 2018 at 18:50, Kalle Olavi Niemitalo wrote:
> I had a problem where my email provider's IMAP server closed the
> connection while Gnus was splitting received mail to nnml
> folders, and Gnus was then unable to expunge those messages from
> the server.  I worked around it by customizing the mail-sources
> variable and adding various date limits to the predicate.
> I hope this information will help someone else.

Interesting and very helpful!  I am forced to use outlook at work and
found that splitting often failed due to this same issue.  I stopped
using splitting for this server.  I may have to try again but it
definitely would be nice if gnus would cater for servers that time out
frequently.

-- 
Eric S Fraga via Emacs 27.0.50 & org 9.1.6 on Debian buster/sid