After mailing from XOOPS admin, I've received undeliverable mail returned from some hosts who require a valid MX record. In short, here is the reason for the returned mail:
Your domain servername.hostname.com does not have a valid MX DNS record.

When I send out a test mail and view the headers, they do not give the email address as the from but list the host server name instead. Can someone point me to how this can be resolved. Is it on my end, XOOPS or the host?

Thanks in advance.
C