Authenticated SMTP to Prevent Blacklisting

When running the application with a few thousand emails from within an Azure environment, it was quickly blacklisted.

After some investigation, it seems that SMTP requests over port 25 are fraught with spam and are used by botnets. The application's behaviour was flagged as such.

I also discovered that one of the outbound IP addresses the Azure app was using was listed on Spamhaus' list. Spamhaus recommends that email clients use port 587 instead of port 25.

Is it possible to configure the application to send SMTP requests over port 587 instead of port 25. If so, how would I go about this?

The issue names no files, tests, or entry points. Start by locating the application's SMTP configuration and checking how the outbound port is selected; done means providing a supported way to send through port 587 instead of port 25 and documenting how to configure it.

Written by the indexing model from the issue text.