Enhance "Send test email" to include information that allows identifying "the test that was being performed."

Currently when a phpBB operator uses the "Send test email" from ACP, they receive a message which contains a static subject and static content (save for the recipient's username in the message body).

It is not unusual when attempting to setup a new phpBB board, or when attempting to troubleshoot a board on which mail delivery suddenly has issues, to need to invoke the "Send test email" multiple times.

But upon arrival of the test email, if and when the test email ever arrives, it isn't possible to know "in response to which test was this email generated?"  i.e. Am I receiving an older email with settings I thought didn't work but were actually just delayed, etc.

There are multiple things we could do, not all of which may be necessary.  But I've listed in a subjective descending order of what seems most helpful:

• Include the current phpBB mail configuration details as part of the message content, so that the admin knows what settings were in effect when the test email was sent.

Anything that would affect successful sending; "Email package size", "Contact email address:", "From email address:", "Force from email address:", "Use SMTP server for email:", SMTP details if they are being used, etc.  Obviously not with sensitive password information included; but it should at least include the SMTP login username, if any.

• Send the "local time" (at least according to user's UCP time zone configuration) that the test mail was generated from phpBB's perspective.

• Maintain and include an auto-incrementing "Test message #" that is displayed in the ACP and included in the subject line and message body of the test message.

• Allow optional entry of a unique statement or multi-line description to be sent as part of the test message, so the admin can describe what test they were performing if desired.  Maybe an ajax box that pops up upon invoking "Send test email" to allow the optional additional text to be prompted for, before then committing to the send.

• Or simply present the generated subject line and message content in that ajax box, and allow the phpBB admin to change whatever they want before sending.

e.g. My hosting service had balked at the static "test message" subject line as having been previously reported as known spam, before I switched away and starting using an external SMTP service.  But there was no easy way to "try the test message with different subject lines" except to go find and edit the language template.