I'm working with a client who has a standard DNN setup. We've stepped through several upgrades to see if that would resolve anything (v7.# and now on 09.00.01).
The issue is, we're getting the following error at random:
InnerMessage: Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host.
We've tried local relay settings, Mandrillapp, Mailgun...
Pardon my vague message, but I don't have much to go by here. I'm more or less someone has had this issue, a light bulb goes off, and I get a miracle fix!
My next step is to replace current mail functions with a custom solution that repeatedly reattempts the sending of the mail, catching more information.
I do know that all methods being used to send mail are calling the DNN core methods.
Thank you for any pointers or advice!