Hi

I have a lot of 1040 errors in the application event log, and mail flow doesn't really always work as expected. Most of the time
there is no problem, but sometimes sending emails remain in the outbox, and are sent only after a while.

I found that this happens, when there are a lot of emails with attachments bigger than 2mb, and I think it that case its an expected behavior, isnt it? But I also see this error during the night, when there is no mail flow (according to message tracking).

This is a virtualized exchange 2013 server running on Hyper-V with all the roles on it. The server has 6 cpus and 24gb ram, and hosts only about 200 mailboxes.

During searching the internet for a solution someone recommended to set the following values:

Set-TransportService MaxConcurrentMailboxDeliveries 50 (default 20)
Set-MailboxTransportService - MaxConcurrentMailboxDeliveries 50 (default 20)

Can anyone tell me if these settings are ok?
What are possible reasons for this error and what can I do to solve this mail flow issue?

Regards
Peter

• Edited by PeterN22 35 minutes ago