Unknown address error 550-'You are not allowed to send mail:sv25.verizon.net. ????

First, my internet and email details:

ISP: Verizon
Email Account: university email (i don’t use my Verizon email)
POP server: pop.jhu.edu
SMTP server: smtp.jhu.edu
Email client: Thunderbird

This setup has been working flawlessly for two years, then tonight i sent a couple of emails out and got the following messages:

Message 1:

Message 2:

The recipients are both people with whom i have corresponded frequently in the past, without incident.

I Googled the error message, and most of the hits revolved around an incident about a year ago when Verizon, for a few days, apparently blocked a just about any incoming email from Europe. I couldn’t fiond anything directly related to my problem, and was especially confused because the email account from which i sent the messages was not even a Verizon account. Also, while one of the recipients is a Verizon account, the other is not.

Not only that, but if i send an email to my wife, who is also on a jhu.edu email account, i don’t get the error message, and she receives the email just fine.

I spent a rather frustrating half-hour or so on the phone to Verizon. The first thing i had to do was try and convince the woman that, given its past two years of problem-free operation, the trouble was unlikely to reside in my use of Mozilla Thunderbird.

She got me to send an email through the web-based version of my email account, and the fact that i got an error message there too finally convinced her that Thunderbird was not the problem.

About half the time on the phone was spent sitting there while she thumbed through the manual trying to work out the problem. In the end, she told me that she spoke to a “Level Three tech” who informed her that Verizon was having trouble with its mail servers.

This partially mollified me, but i also wondered whether this could really be the cause of my problem, given that my own email address goes out through my school’s smtp server, and at least one of my recipients is not a Verizon email address, but a Bell Atlantic email address.

She didn’t seem convinced that this was really the problem either, but she told me that they expected to have the email problem fixed by tomorrow, so i decided to cut my losses and see if it works by tomorrow evening.

Given my explanation of what happened, does her explanation of the cause of the problem sound plausible? Has anyone had experience with these sorts of errors?

Bell Atlantic is Verizon, or at least has been since it acquired GTE in 2000.

You don’t have a problem with Verizon blocking SMTP traffic on port 25 since your wife can receive mail, so I’d guess that Verizon’s having trouble with its mail servers and is bouncing messages. Have you been able to send mail to anyone on a non-Verizon, non-JHU account?

Aha! At least that suggests, as you say, that it’s a problem with Verizon and not my email. I haven’t yet tried to send an email to a non-Verizon, non-JHU account. Maybe i’ll give it a go.

A message sent to the Verizon account from my Gmail account apparently arrive, though, because i didn’t get a return undeliverable message.

I work for a firewall company and do a lot of email troubleshooting.

It’s difficult to say for sure from the error message, but its sounds similar to what you might get if the mail server at your university had been blacklisted by those you are trying to send to for excessive spamming or something of that nature.

It could also be a case of the recipient mail servers having some kind of a temporary problem which may clear up once the administrator figures out something isn’t working right.

And, you are correct, a good test would be to send to a few other addresses to get a better idea if it happens everywhere.

Thanks for the advice.

I did send an email to an AOL account a little while back, and got no error message, so it seems to be a problem only with Verizon accounts. It could be that they’re blocking the university or that they just have a problem, as you say. I’ll try sending to those addresses again tonight and see what happens.