Follow up:
I decided to also try sending mail to verizon with your address,
iforbes@???. And received the same error as you encountered, after an
extremely long time delay. This bothered me, so I tried sending a mail from
a non-existant domain, and immediately received a 550 error telling me I am
not allowed to send mail. Error 550 is usually sent to deny relaying after
an RCPT TO: command for an address the server does not own or relay for.
Sending 550 after MAIL FROM: is unusual, but verizon probably feel it is
necisary.
This leeds me to believe that these servers perform a practice known as
sender verification. Though not uncommon, it is combersome and creates long
wait times and alot of DNS traffic overhead. Basically, once you send the
MAIL FROM: command, the server first performs a DNS lookup on your domain,
once it has found the domain to exist and have a valid MX record, it
connects to the MX listed and attempts to send a mail back to the sender,
disconnecting just after RCPT TO: was accepted.
This helps to prevent spam, but causes several problems. I have a hunch
there is probably some issue with DNS or your primary MX, or perhaps a
connectivity issue between you and verizon which does not allow the verizon
server to connect back to yours. This could occur if a major overseas line
is down and asymetric routing is being used to compensate.
I don't know what else it can be. Check your DNS and mail servers, and phone
your ISP and make sure their network is functioning properly.
Will
----- Original Message -----
From: "Willie Viljoen" <will@???>
To: "I. Forbes" <iforbes-exim@???>; <exim-users@???>
Sent: Tuesday, November 04, 2003 3:26 PM
Subject: Re: [Exim] OT: Problem sending mail to verizon.net
> This is from a machine in Bloemfontein, SA, on the old SBS network, to the
> same server you tried. The hostname is apollo.laserfence.net and reverse
DNS
> records resolve that same name. I first tried my normal e-mail address,
> will@???, and it worked fine. Then I tried another address,
> will@???, which was also accepted.
>
> %telnet relay.verizon.net 25
> Trying 206.46.170.12...
> Connected to relay.verizon.net.
> Escape character is '^]'.
> 220 sc003.verizon.net MailPass SMTP server v1.0.6 - 103003062626JY ready
> Tue, 4 Nov 2003 07:17:31 -0600
> HELO apollo.laserfence.net
> 250 sc003.verizon.net
> MAIL FROM:<will@???>
> 250 Sender <will@???> OK
> QUIT
> 221 sc003.verizon.net closing connection
> Connection closed by foreign host.
> %telnet relay.verizon.net 25
> Trying 206.46.170.12...
> Connected to relay.verizon.net.
> Escape character is '^]'.
> 220 sc010.verizon.net MailPass SMTP server v1.0.6 - 103003062626JY ready
> Tue, 4 Nov 2003 07:18:16 -0600
> HELO apollo.laserfence.net
> 250 sc010.verizon.net
> MAIL FROM:<will@???>
> 250 Sender <will@???> OK
> QUIT
> 221 sc010.verizon.net closing connection
> Connection closed by foreign host.
>
> It works from this machine. I also decided to try it from mail.act.co.za,
a
> machine in Kroonstad, SA, which has reverse DNS resolving it as being
inside
> the .ZA domain. Again, both addresses were accepted:
>
> %telnet relay.verizon.net 25
> Trying 206.46.170.12...
> Connected to relay.verizon.net.
> Escape character is '^]'.
> 220 sc017.verizon.net MailPass SMTP server v1.0.6 - 103003062626JY ready
> Tue, 4 Nov 2003 07:21:00 -0600
> HELO mail.act.co.za
> 250 sc017.verizon.net
> MAIL FROM:<will@???>
> 250 Sender <will@???> OK
> QUIT
> 221 sc017.verizon.net closing connection
> Connection closed by foreign host.
> %telnet relay.verizon.net 25
> Trying 206.46.170.12...
> Connected to relay.verizon.net.
> Escape character is '^]'.
> 220 sc011.verizon.net MailPass SMTP server v1.0.6 - 103003062626JY ready
> Tue, 4 Nov 2003 07:21:28 -0600
> HELO mail.act.co.za
> 250 sc011.verizon.net
> MAIL FROM:<will@???>
> 250 Sender <will@???> OK
> QUIT
> 221 sc011.verizon.net closing connection
> Connection closed by foreign host.
>
> Try sending your mail again. It could be that this was a temporary problem
> at verizon, for instance, a spam checking service not functioning. When I
> perform the commands manually, there is a long time delay after sending
the
> MAIL FROM: command. It could be that this server is checking with spam
> listing services before accepting a sender. If such a service was down, it
> would cause this problem. Also, check to make sure you are not currently
on
> any popular spam blocklists, for any reason, these lists can sometimes
list
> you accidentally, or because of a problem you are unaware of.
>
> Hope this helps.
> Will
>
> ----- Original Message -----
> From: "I. Forbes" <iforbes-exim@???>
> To: <exim-users@???>
> Sent: Tuesday, November 04, 2003 3:09 PM
> Subject: [Exim] OT: Problem sending mail to verizon.net
>
>
> > Hello All
> >
> > This is a bit off topic, but perhaps somebody can shed some light on
> > this problem.
> >
> > Our customers are complaining they can't send e-mail to addresses of
> > the format <user>@verizon.net.
> >
> > It seems their main incoming relay is doing some checking at the
> > "MAIL FROM:" command and the session times out.
> >
> > nimbus2:~# telnet relay.verizon.net 25
> > Trying 206.46.170.12...
> > Connected to relay.gte.net.
> > Escape character is '^]'.
> > 220 sc006.verizon.net MailPass SMTP server v1.0.6 - 103003062626JY
> > ready Tue,
> > 4 Nov 2003 04:16:15 -0600
> > helo nimbus2.zsd.co.za
> > 250 sc006.verizon.net
> > mail from:<iforbes@???>
> > 450 Requested mail action not taken-Try later:sc006.verizon.net
> >
> > It seems the problem occurs when the mail from address is hosted in
> > South Africa. I have tried a number of them without success,
> > "hotmail" addresses don't seem to work either, but when I put in an
> > address hosted in Europe, it works.
> >
> > Any suggestions, I can't even send e-mail to <postmaster@???>
> > address? (Maybe someone can forward this to that address)
> >
> > Thanks
> >
> > Ian
> >
> >
> > --
> > Ian Forbes ZSD
> > http://www.zsd.co.za
> > Office: +27 21 683-1388 Fax: +27 21 674-1106
> > Snail Mail: P.O. Box 46827, Glosderry, 7702, South Africa
> >
> >
> >
> >
> > --
> >
> > ## List details at http://www.exim.org/mailman/listinfo/exim-users Exim
> details at http://www.exim.org/ ##
> >
> >
> >
>
>
> --
>
> ## List details at http://www.exim.org/mailman/listinfo/exim-users Exim
details at
http://www.exim.org/ ##
>
>
>
