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 FileMaker Pro Custom Functions

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IsValidEmailƒ ( _email )

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  Average rating: 3.6  (60 votes)
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Michael Rhodes, Allied Data Service

test if valid email for format and against current top level domains

Sample Input:
IsValidEmailƒ ( "" )
Sample Output:

 Then copy & paste into FileMaker Advanced's Edit Custom Function window.

Click here to copy To Clip Manager if you have myFMbutler's Clip Manager installed


IsValidEmailFormatƒ is a better choice in most situations, since top level domains are constantly created. However, for those who want to test both the format of the email and make sure the top level domain is legitimate according to the current list as of creation date, here is this alternative.

Note: these functions are not guaranteed or supported by Please contact the individual developer with any questions or problems.

This is my Custom Function and I want to edit it


5 most recent comments | Show all 12 comments

I really don't like this function because the top level domains can change. Please use my similar custom function IsValidEmailFormat.

Michael Rhodes, Rancho Cucamonga
December 05, 2010 8:19am

Try the update I just posted.

Michael Rhodes, Rancho Cucamonga
December 05, 2010 8:30am

Great function. However, the ampersand (&) is a valid character in an email address.

Jamie Thompson, Computech IT Services Ltd., Plymouth, UK
March 10, 2011 4:26am

Unfortunately, this doesn't properly validate *any* multi-part domains, like the Office 365 native domains that look like "". Paolo's modifications allow it to work for those as well, however.

John, PA
April 16, 2014 7:57am

This function allows an underscore character to be in the domain name part of the address (after the "@"), but an underscore is not a legal character in a domain name (it's fine in the username part, i.e. before the "@").

There is apparently some argument about whether underscores are *technically* permitted by the RFCs in the domain part, but in practice they are *not* allowed and will be rejected.

So to validate the domain part properly to allow only alphanums, hypens and dots, I added this line to this function, just below the first "Filter" statement:

and Filter (dom; alphanum & "-.") = dom // There are only alphanumerics, dashes and dots in the domain

JohnD, PA
May 19, 2015 11:53am

Make a comment about this Custom Function (please try to keep it brief & to the point). Anyone can post:

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