Hi-
We send emails to our patrons via DBTW. When we click the 'send emails" button lately, some (not all) emails don't get sent. We get the message "x emails sent, x not sent" and the log file has this note:
5/6/2009 12:42:32 PM: Failed to send message to '[PATRON'S EMAIL ADDRESS HERE]' using SMTP: 'There was a problem with the server with the RCPT command.'.
Any ideas? Our IT folks can find nothing in the mailserver log that looks fishy, nor can I find any relevant firewall or other security issues.
Thanks

I may have fixed the problem: our patron database has email addresses in UPPER CASE. Changing everything after the @ to lower case appears to have resolved this issue.