Regular expressions can be very useful and efficient if used properly. For a while now in some of our applications we have been using the following regular expression to check e-mail addresses for proper formatting.
^[_a-z0-9-]+(.[_a-z0-9-]+)*@[a-z0-9-]+(.[a-z0-9-]+)*.(([a-z]{2,3})|(aero|coop|info|museum|name))$This will ensure that the user has entered a properly formatted e-mail address such as user@domain.com.
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This is fantastic.
But, how do you validate for an address of
the following format
first.last@something.abc.af.mil
or
first.longlast@long.base.navy.mil
This regular expression has been updated to check for capitalization in e-mail addresses.
[…] We discovered a small bug in our old regular expression for checking valid e-mail addresses. When a user tried to use an address with capital letters on a form, it failed to match the regular expression. We updated the regular expression to account for capital letters anywhere in the e-mail address. […]
Don’t forget about arpa!! The expression should be
^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*\.(([a-z]{2,3})|(aero|arpa|coop|info|museum|name))$