Unsolicited Bulk Email abuse - Exchange 2003
We have sudenly lost the ability to send external e-mails! Eveything has been fine for months and nothing has changed on the exchange server. Then last night e-mails I was sending were getting returned with the following message:
Your message did not reach some or all of the intended recipients.
Sent: 31/03/2010 9:14 AM
The following recipient(s) could not be reached:
**firstname.lastname@example.org on 31/03/2010 9:14 AM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<**server-address**.internal #5.5.0 smtp;550-Your server is a current source of Unsolicited Bulk Email abuse. Please>
The above was just a test but it happens with any external address and any user.
I have used a website called MX Lookup Tool - Check your DNS MX Records online - MxToolbox to check if we are on a blacklist but we are not on any of them.
I have logged a call with our ISP about this but if you guys have any suggestions I would be greatful.