Hi, I am using Small Business Server 2003. It has been working without any problems, but today, I am experiencing problems sending email. Some messages are being returned with the following undeliverable report: There was a SMTP communication problem with the recipient's email server. Please contact your system administrator. <mydomain.com #5.5.0 smtp;550-Verification failed for <my.name@mydomain.com>> There does not appear to be a pattern to how this happens, or which email addresses the mail is bouncing back from. Can anyone advise what the cause could be? Thanks

How do you route your email? If you are going out through a smart host then the issue is with them. You will need to speak to them to see if they have changed something. If you are sending your email by SMTP, then you should be getting a variety of error messages unless the domains that you cannot send email to are all using the same SMTP scanning service (Postini, Message Labs etc). There will be a pattern, you just need to establish what it is. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources