Problem: Exchange Error 450 4.7.1 Error: too much mail from x.x.x.x

Messages being sent out of exchange are being queued up with the error 450 4.7.1 Error: too much mail from x.x.x.x (where x.x.x.x represents the external IP of the mail server in question).  I got this information from another admin who is trying to send email to my domain.  I am receiving emails no problem from other companies.  I am running exchange server 2003 on my end.  The admin at the other company is also getting “450 4.5.0 no recipient succeeded” error message for mail destined to my domain.

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Solution: Exchange Error 450 4.7.1 Error: too much mail from x.x.x.x

Found the solution in another post.  Turns out I had a certificate loaded on my Default SMTP Virutal Server.  Right click on Default SMTP VIrutal Server and choose Properties.  Go to the Access tab and then click on the Certificate button.  There will be an option there to remove your current certificate.  Once I did this the mail that was queued up to be delivered to my exchange server started to come through.  Not sure if this is significant or not but I use an internal CA (certificate authority) which is maybe why a proper session could not be established with my server.  I assume that because only certain domains had issues sending to me that they must have had TLS enabled whereas the other domains that I was receiving email from without issues probably did not have TLS enabled for their outgoing mail.