Access InputMask question

[gcapp]

Ok, I need an Access expert for an input mask that I can't figure out.

I want an input mask for an email address that has 6 letters required before the "@" symbol and 6 letters after, with 2 being required and the other 4 optional and then ".cattco.org"

How the only thing I came up with is this:

LLLLLL"@"LL????".cattco.org"

Now the problem is that it leaves blanks if I don't type in the optional 4 letters like:

abcdef@gh____.cattco.org

I need it where I can type in a minimum of 2 letters and the blanks will disappear and result like:

abcdef@gh.cattco.org

Can someone help??

Thanks,
Gary