[Tfug] 501 HELO requires valid address

[Adrian]

On Wednesday 13 June 2007 20:20, christopher floess wrote:
> Hi, everyone. Been using it for years, only now for the first time I want
> an email client instead of webmail, and I'm realizing I don't know sh at t
> about email.
> 
> I'm setting up Sylpheed with multiple accounts, and I got gmail set up,
> but when I try setting up my other email, I get the error in the in the
> subject. I don't know what this means. I've done some research, and
> a while back when I first started to tinker with an email client and got
> the same errors, I actually ended up at a tutorial that had me telnet
> into some server somewhere, and send a message manually. While
> that was interesting, it didn't help me solve the problem.
> 

>> 501 HELO requires valid address

... The subject line says it all... Based on your description, the problem is 
that you do not have or are not sending a valid hostname when trying to send 
mail. SMTP is a multi-step process which may or may not be checked and/or 
rejected at various stages by the receiving server (not, it may not reject on 
an error immediately, instead waiting till later in the conversation).

So... a 5xx is a permanant failure, i.e. don;t try to send again, it's not 
going to work.

HELO is a basic form of the initial SMTP greeting (EHLO is the advanced form), 
which expects a FQDN argument (Fully Qualified Domain Name). Your FQDN should 
be just that, fully qualified with a proper domain name structured, though it 
doesn;t neccessarily have to be resolvable by the remote end. Many ISPs 
filter based on HELO (particularly traffic from external IPs) as it is often 
a good indicator of bots/compromised machines. A "good" sender will HELO as 
"HELO mail.acme.com", a typical bot will HELO as "HELO 8931231914" or "HELO 
bobs-computer".

So... my first suggestion would to check your hostname. My second suggestion 
would be to investigate why you can send in one client and not in another. My 
guess would be that they are NOT set the same... Ignore the POP/IMAP 
settings, you need to look at the SMTP/sending server sttings. My guess is 
that one is set to send SMTP to your ISPs client side mail server, the other 
to the externally available server which no doubt checks HELO.

Adrian