(#17827) Properly format SMTP HELO when sending tagmail

Previously, the tagmail report sending code did not initialize
Net::SMTP.start with a 'helo' option, which causes securely-
configured SMTP servers to reject the mail.

This commit adds settings to control the destination SMTP port
and the value for SMTP HELO, which default to 25 and our fqdn,
respectively.

Report and original patch from Jim Pirzyk.
Merge branch 'pull-1351'

This closes GH-1351