Exchange: Your message has been delayed I/O error encountered
Users are receiving the following Non Deliverable Message (NDR)when sending to third party domains:
Your message has been delayed and is still awaiting delivery to the following recipient(s):
I/O error encountered
In this instance, users were reporting that messages sent to Gmail were being delayed anywhere from hours to days. When telneting to Gmail's mail servers, sometimes it would accept the connection and would allow our server to send mail. However, other times I would receive "Connection lost" immediately. The issue at hand was that this organization sends bulk email to many third party domains.(Not SPAM) Gmail has a specific policy on bulk E-mailing. Therefore, Gmail will temporarily block your domain from sending too much bulk E-mail.
MCSE M+, S+, MCTS, Security+
How useful was this article? Want to see a tip not listed? Please leave a comment.