[Users] [Bug 4104] SMTP doesn't work over VPN

[Michal Suchánek]

On Sun, 28 Oct 2018 19:55:53 +0100
Andrej Kacian <ticho at claws-mail.org> wrote:

> On Sun, 28 Oct 2018 18:54:47 +0100
> Michal Suchánek wrote:
> 
> > >     
> > > > These problems tend to affect SMTP
> > > > earlier than IMAP but over time both protocols are affected and
> > > > claws cannot do any networking until restarted.      
> > > 
> > > It would be good to see some justification of these statements.    
> > 
> > What do you want as justification? It just breaks from time to time.
> > Not often enough to see a pattern that warrants a bug report. No useful
> > information in the log either.  
> 
> Have you tried attaching strace, or gdb to the claws-mail process when
> it's in that "state", and looking at what happens when it tries to
> access network? I'm not saying it will reveal something obvious, but it
> might be worth looking at that...

Looks like problem is quite simple. claws uses a child process to
connect to the SMTP server. There is a memory leak in claws which
causes it to increase its memory footprint over time. At some point the
claws process is so big that the kernel thinks it cannot be forked and
fork() returns ENOMEM. Then SMTP stops working. Restarting claws
decreases the memory footprint again leading the SMTP working again.

Thanks

Michal