If "@" $ fieldname
   MessageBox("Valid e-mail")
Else
   MessageBox("Not valid e-mail")
Endif

OR

MessageBox(IIF("@" $ fieldname, "Valid e-mail", "Not valid e-mail"))

>How can I check a e-mail by adapting the idea below
>
> if field contains @
> = messagebox "valid e-mail"
> else
> = messagebox " not a valid e-mail"
>endif