If the machine from you are sending mail doesn't have a
FQDN and the mail server requires a FQDN in HELO the
current code will fail.

Resolving the name it's a very bad idea:
- It's something from other layer (DNS/IP) not from SMTP
- It breaks when the name of the computer is not FQDN
(as many dial-ins do) and the SMTP server does strict
EHLO/HELO checking as stated before.
- It breaks computers with a TCP tunnel to another host
from the connection is originated if the relay does
strict EHLO/HELO checking.
- It breaks computers using NAT, the host that sees the
server is not the one that sends the message if the
relay does strict EHLO/HELO checking.
- It's considered spyware as you are sending
information some companies or people don't want to say:
the internal structure of the network.

No important mail client resolves the name. Look at
netscape messenger or kmail. In fact kmail and perl's
Net::SMTP does exactly what my patch does.

Please don't resolve the names, as this approach works
and the most used email clients do this.

I send you the bugfix.