Amazon SES worker has unused $_SMTP variable

[kareila]

Again from @alierak pointing out that there's a variable in send-email-ses that looks like it was intended to cache an open SMTP connection and reuse it across requests, but the variable is never assigned a value other than undef.

[kareila]

Reopening because this wasn't working in production.

[alierak]

With caching, we started to see odd failures when a connection was reused, mostly "Error during MAIL phase... 000" or "Error during MAIL phase... 599 Connection closed". I think when grabbing a connection from the cache it's probably going to be necessary to issue some command on it like a RSET or whatever just to check whether it's still open. Unfortunately the behavior of RSET with respect to SMTP AUTH state is not well-defined, so maybe NOOP would be the right choice to test the connection.

[alierak]

Naturally Net::SMTP{S} exposes a reset method but not noop.

[alierak]

Alternatively I guess we could check specifically for return codes of 000 and 599, tempfail those and drop the cached connection.

[alierak]

Looks like it does have a _NOOP method, so that might work anyway.