Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1004
  • Last Modified:

SMTP Communication Error 5.5.0

I have looked all over in here for answers to issues related to this problem. I have tried all the answers that people suggested....

This is the issue....
There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
<nwex0.ideas.ad #5.5.0 smtp;500 Syntax error, command unrecognized>

We have a Watchguard Firebox 1000 as our firewall, we have two exchange servers that communicate with eachother so disabling the ESMTP verbs i do not think is an option, as the two exchange boxes would not communicate.

This error is sporadic, mostly happens when emailing hotmail, but has since been erroring out when communicating with other email addresses as well.

I have checked the blacklists to see if we are blacklisted, our exchange server IP is, we are not on any blacklists.

Please help as have limited knkowledge, but will try what you suggest.


  • 2
  • 2
1 Solution
IDEASITAuthor Commented:

I have already looked into this document and it did not help me with solving my issue. Any other suggestions anyone?
IDEASITAuthor Commented:
Okay here is what i found, after searching and working for hours on this issue.

This article explains the issue in a little more detail...

I found this on Watchguards website, you must be a registered user on thier site to view it

I originally had one rule for SMTP, which i used for both incoming filtering and outgoing filtering and proxy.

After reading this article, i decided to delete my SMTP rules and create two new rules, one for incoming and for outgoing, instead of proxying i used the SMTP filtering on the outgoing rule which will allow our mail server to communicate better with the outside world. (See article for how to add this rule)

Thanks for your help.

I solved this myself...so do i get the points????
sure u do.glad things worked out for u...ask the admin to refund ur points...take care and good luck...

Featured Post

Get expert help—faster!

Need expert help—fast? Use the Help Bell for personalized assistance getting answers to your important questions.

  • 2
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now