Temporary mail queue services?

[tonyb at go-concepts.com (Tony Bunce)]

> Does anyone know of a service that you can sign up for to add as a secondary
> MX to act as a mail queue if your primary MX isn't available?

Here is one that I have heard of in the past:
http://www.junkemailfilter.com/spam/free_mx_backup_service.html

I have never used it though.

-Tony