[CentOS] grep pattern x, but not pattern y on the same line

Hi folks

I have the command "find . | xargs grep 'mailx'", to search all files
with "mailx" in contents. I wish to add a second condition that NOT
contains string sven.aluoor at ubs.com on the same line.

Every file which contains "mailx", but not the string
sven.aluoor at ubs.com in the same line.

cheers Sven