Trying to come up with some clever way to validate email adresses is bound to fail. The actual correct regex would be something like four pages long, and that's ignoring the fact that there is no single correct solution.
For instance; your regex will consider completely valid .group email addresses to be invalid.
Just check if there is an @ somewhere in there and leave it at that. If you really must know if an address is valid, you should send a token to it and ask the user to confirm the token.
Hi Razvan,
You need to escape the character (since in mendix ' is used to start/end a string), which can be done by preceding it with another '