net/smtp: add optional Hello method

[bdaglish]

net/smtp is hardcoded to send "HELO localhost" and "EHLO localhost"
. This can cause blacklisting problems - see the "Identifying the Problem
Area" section of http://cbl.abuseat.org/namingproblems.html . This should probably
be configurable, defaulting to os.Hostname() if not specified.

[rsc]

Comment 1:

I don't believe we can change the default behavior now, nor do I believe it is
desirable. However, it would be fine to introduce an optional Hello method to override
the default of "localhost".
http://golang.org/cl/5555045 contains an implementation, and the comment thread
contains a long discussion about the choices. I hope someone will pick up that CL and
finish it, mainly by writing a test.

Labels changed: added priority-later, removed priority-triage.

Status changed to Accepted.

[rsc]

Comment 2:

Labels changed: added size-m.

[rsc]

Comment 3:

Labels changed: added suggested.

[gopherbot]

Comment 4 by rickarnoldjr:

Fixed by https://golang.org/cl/6946057/

[rsc]

Comment 5:

This issue was closed by revision 475dee9.

Status changed to Fixed.