dovecot - Apr 2019 - Problem with filter forwarded messages when using director proxy

Hey there,

I've been able to switch our mailservers over to using director to proxy 
logins and received email to the backend servers which store email on a 
shared NFS mount.? Before I did this we were having trouble with the 
indexes running into errors because multiple servers accessing and 
modifying the dovecot.index files at the same time.? I'm still seeing a 
small amount of this, and tracing it through it appears that when an 
account uses a filter to forward email to another address within our 
mail system, it recognises that it is a local email address it is 
responsible for and saves the message locally despite the fact that it 
is not the director specified server for the recipient address.

As an example, lets say that test1 at example.com is currently pointed to 
the 01 backend server by director, and test2 at example.com to 02. If a 
filter at test1 forwards email to test2, then when an email for test1 
comes in the director porxy will direct it to the 01 backend server, and 
when the message is saved the filter will run to forward it, and the 01 
server will recognise that it is also responsible for test2 and so 01 
will save the message for test2 rather than 02, as per director.? This 
is causing a smallish number of clashes which I'd like to get cleaned up.

I've tried getting the server to send through a relay but if it 
recognises the account as local it will not use the relay to send the 
email.? Has anyone run into anything like this or have any ideas about 
how to approach the problem?

Thank you
Ted
easyDNS Technologies