On Thu, Jun 24, 2010 at 06:55:47PM +0200, Luciana Moreira wrote: > Hello Wietse, > > Thx a lot for your quick reply. > > I thought that the client side concurrency was defined by: > > 1) lmtp_destination_concurrency_limit
Per nexthop, provided the transport is called "lmtp", and not something else. Do you route multiple destination domains to the LMTP transport? If so, use a consistent nexthot destination "lmtp:[lmtp.example.com]" However, if LMTP delivery is indirect, via mailbox_transport, then the LMTP concurrency ceiling is actually determined by the process limit of the local(8) delivery agent, since it is local(8) and not the queue manager that hands off mail to lmtp(8) via mailbox_transport. > 2) the number of lmtp processes This is enforced by the master process and is a hard limit. If you appear to be exceeding it from time to time, it is most likely the result of connection caching. > I have set them both to 1 now and still get the same error message. So I am > starting to believe that there must be yet another configuration that I am > unaware of. I have read many pages on the topic but haven't yet seen > anything different from what I have done. > > What I am missing? Disable LMTP connection caching if you must ensure a concurrency limit of 1. Typically the server concurrency limit is much higher, and the client concurrency limits fit well within the server's limit. -- Viktor.