More email sending problems.

Some people are getting errors at the HELO command.

Blitzmail just sends "HELO Blitzmail" but some servers apparently require "the host name of the client system"

How do I find this?

I think you do:
HELO " + DottedIP$(HOSTIP(1))

Cheers, seems to make sense.

Okay that worked, but now he's getting an error further on.

SENDING: HELO xxx.xxx.0.3
COMPUTER SAYS:250 smtpout.xxx.xxx.com Hello xxx.xxx.0.3 [xxx.xxx.xxx.xxx]
SENDING: MAIL FROM: <xxx@...;
COMPUTER SAYS:250 OK
SENDING: RCPT TO: <xxx@...;
COMPUTER SAYS:250 Accepted
SENDING: DATA
COMPUTER SAYS:354 Enter message, ending with "." on a line by itself
Sending Message Contents
Encoding file attachment...
--boundarystring
Content-Type: application/octet-stream; name=undo\temp_893_21060__gamestate.NWTc
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename=undo\temp_893_21060__gamestate.NWTc

(encoded file contents not displayed)

--boundarystring--
COMPUTER SAYS:550 Administrative prohibition    <---------------ERROR
COMPUTER SAYS:221 smtpout.xxx.xxx.com closing connection

Any idea what's causing the "Administrative prohibition" error?

The 550 error usually relates to blacklisted email addresses or relaying.

It may have something to do with the HELO IP address being an internal one rather than the external address.

Any suggestions?