Up till now the only way to do what you're asking was to modify the code within FormMail.
But we liked you're idea so much, that we've implemented it as a standard feature.
The new version is 2.05 and it's attached below. You need to change a new configuration variable which is around line 1032.
Change it from:
$CSVQUOTE = '"'; // all fields in the CSV are quoted with this character;
In other words, make it an empty string.
$CSVQUOTE = ''; // all fields in the CSV are quoted with this character;
Please let us know how you go with the attached version, and if all is OK, we'll release it generally. (We have tested it quite extensively before giving this to you.)