Could not instantiate mail query - again!!

[burlington]

I have seen the previous postings on the Forum about this phrase.
CMSMAS site running 1.11.10
CMS mailer works fine & sends test messages. Set to 'mail' as the mailer method (nothing else works!). From address is root@domain name
However, Form Builder, version 0.7.3, does not send any messages.
From address is root@domain name and there is an email address like this on the server.
I am completely baffled. This is the first time I have had this problem.
Any ideas would be appreciated.
Many thanks
Martin

[Dr.CSS]

Make sure the "from email address" in CMSMailer and formbuilder are a real email address for that domain or at least read like it is and not using root@...