mail2 issues causing this?

[thingwarbler]

A client is complaining. They are seeing this:

“Hi. This is the qmail-send program at mail2.g********.com.
I’m afraid I wasn’t able to deliver you message to the following addresses.
This is a permanent error; I’ve given up. Sorry it didn’t work out.
[email protected]
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.â€

The recipient address is legitimate. Can I tell them this was caused by hardware issues and has been resolved, or...?

 

[Stephen]

It should not have happened, it sounds like something else. the hardware issue I am checking tomorrow is not hampering usage now, just if there was to be heavy load it is a bit low on RAM for some reason since some chips not working, but that is an unrelated matter to this or the power supply/motherboard going out.