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#5.5.0 smtp;550 Invalid recipient

Posted on 2005-03-25
Medium Priority
Last Modified: 2008-06-02
I have searched and searched for answer to my question and I have done a set type=MX on the recipient - and got a reply back - this is the message I am geeting when send to recipient

here was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            <******.*****.com #5.5.0 smtp;550 Invalid recipient <*****@******.com>>

I was able to send to the recipient from my yahoo account fine - But cannot send succesfully from my exchange server - It always gets bounced back - I made sure my server was in the DNS foward look up - If you cant tell I am kind of new to this and I cannot find a valid answer and how to correct it -

I think the recipient is using an external mail server that is hosted by "speedfactory" - I was able to find this out by using Reverse DNS look up - It seems I have all the pieces - I just cannot figure out how to put them together - Thanks in advance -
Question by:modest911
  • 4

Author Comment

ID: 13631144
exhange 2000
LVL 20

Accepted Solution

What90 earned 1500 total points
ID: 13634297
Can you send to other addresses from the Exchange server without problems?
If you can then check there isn't any spelling mistakes in the email address

If you can't then from a cmd prompt on your exchange server type telnet mailserver.domain.com (replace this with the name of the remote server you're trying to connect to) 25

If the connection fails your ISP may be blocking port 25 from sending. Check with them if that's the case.

Author Comment

ID: 13636059
Yes I can send to other addressess fine -

No there is no spelling mistakes in the e mail addy

Thats the thing how will I know what there mail server name is? I dont think they have an IT person at there location that I can talk to - Is there any other way for me to figure out what the name of there mail server is?
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Author Comment

ID: 13647385
Okay here is the update - I was able to telnet into what I think the receipt is using for a mail server - Before I was trying to use clients.speedfactory.net and open on port 25 but I didnt get any responce - Today I used the ip that I received from the revers dns look up and was able to open them up on port 25 ?!?! now what

Author Comment

ID: 13647412
But the responce I got when telnetting into the ip was ESMTP "domain name" MDaemon 7.1.0

Expert Comment

ID: 21691266
I'm having the same problem.  I can send from my exchange server to the recipient, but not from my clients exchange server to the recipient.  It fires back the following NDR straight away.
I can telnet to the recipient's mx record on port 25 from my clients server no problem.

'Some, One - ECS' on 02/06/2008 10:00
            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            <My Server #5.5.0 smtp;550-Invalid recipient

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