some clients of mine got this bounce message when mailing me on Friday -
< ***@*****.com>:
Sorry, I wasn't able to establish an SMTP connection. (#4.4.1)
I'm not going to try again; this message has been in the queue too long.
Can you ask your clients to get value of "queuelifetime" for their mailserver. This will help understand the issue. Also i would like to know their SMTP addresses.