550 Too Many Invalid Receipients

We do not have our own email server. We got through business.verizon.net but use our owndomainname.com
I have a user that keeps getting this error.  Emails have been addressed to one individual at a time. He's tried typing manually and not using a address book.  At first the error message would only happen when replying to an email.  After 4 weeks of trying to resolved this issue, the problem now happens when sending a new email.  I hope I provided enough information.

Your message cannot be delivered to the following recipients:

  Recipient address: cisqo@clearchannel.com
  Reason: Rejection greeting returned by server.
  Diagnostic code: smtp;550 Too many invalid recipients
  Remote system: dns;external.clearchannel.com (TCP||43378||25) (Too many invalid recipients)

Reporting-MTA: dns;vms115.mailsrvcs.net (tcp-daemon)

Original-recipient: rfc822;cisqo@clearchannel.com
Final-recipient: rfc822;cisqo@clearchannel.com
Action: failed
Status: 5.0.0 (Rejection greeting returned by server.)
Remote-MTA: dns;external.clearchannel.com
 (TCP||43378||25) (Too many invalid recipients)
Diagnostic-code: smtp;550 Too many invalid recipients
Who is Participating?
NopiusConnect With a Mentor Commented:
I just checked connection to that server and your recipient (rcpt to: and mail from: are intentionnally changed):

250 SIZE 41943040
mail from: root@nop-nop.com
250 sender <xyz@nop-nop.com> ok
rcpt to: cisqo _ @ _ clearchannel.com
250 recipient <cisqo _ @ _ clearchannel.com> ok
354 go ahead
Subject: test

250 ok:  Message 76389008 accepted

Everything seems to be working from their server's side.

Now we see that: Reporting-MTA: dns;vms115.mailsrvcs.net (tcp-daemon)
It's not real DNS name, probably it's a fake name inside verizon. But sending IP is:, that resolves as vms115pub.verizon.net.
So I guess that you are sending email from vms115pub.verizon.net. to smtp11.clearchannel.com directly, without using 'business.verizon.net' mail server.

And also I see that  smtp11.clearchannel.com has strong antispam policy. Probably it stops receiving email from you after it has got some number of bad recipients in some period of time. I don't know which emails where bad, but surely not that you have mentioned above. It's better to ask postmaster@clearchannel.com why his server refuses emails from you.

Nilesh RoyConnect With a Mentor Senior Manager - Technology ManagementCommented:
Short and sweet
Query -> Reason: Rejection greeting returned by server.Diagnostic code: smtp;550 Too many invalid recipients
Answer -> Your IP block has been marked as spam host on the receiving server.
Actual reason -> UCEPROTECT-Network Level 2: Network is blacklisted at UCEPROTECT Level 2
URL -> http://www.uceprotect.net/en/index.php?m=7&s=7

Let me know if i am of help.

- Nilesh Roy.

Nilesh RoySenior Manager - Technology ManagementCommented:
Any updates?
LKamokuAuthor Commented:
I'm currently researching both responses.
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