Once in a while you’ll be forced to validate an email address (or many!) — The usual no-brainer method is to perform a quick syntactical test to ensure the address is not malformed, however even a properly formed address may be invalid or, unreachable.
Clearly we must add a second validation step… — Hey I know, let’s check the MX records!
Procedure.s Email_GetHost( eMail.s ) If eMail ProcedureReturn Right( eMail, Len(eMail) - FindString(eMail, "@", 1) ) EndIf EndProcedure Procedure.i Email_ValidateAddress( eMail.s, CompleteValidation.i = #True ) Define.s pattern = "^([_a-z0-9-]+)(\.[_a-z0-9-]+)*@([a-z0-9-]+)(\.[a-z0-9-]+)*(\.[a-z]{2,4})$" Define.i is_valid = #False Define.i handle = CreateRegularExpression( #PB_Any, pattern ) If IsRegularExpression( handle ) If MatchRegularExpression( handle, eMail ) If CompleteValidation Dim mx.s(99) If getmxrr( Email_GetHost(eMail), mx() ) ; see http://gushh.net/blog/2010/07/17/get-mx-records/ is_valid = #True EndIf Else is_valid = #True EndIf Else is_valid = -1 EndIf FreeRegularExpression( handle ) EndIf ProcedureReturn is_valid EndProcedure
For the getmxrr() function click here. Or click here for the full code + example usage
The full code also contains a few other helper routines, I left them in there in case someone finds them useful.
These are the functions included in the source:
Email_GetName() Email_GetHost() Email_ValidateAddress() Email_ConvertToLiteral()
Obviously you’ll have to tweak a bit the code, specially the way it handles the arrays. But overall it should be pretty usable. I might come up with a cross-platform version in the future, but so far I haven’t found a need for it.
Please double-check the example code, make sure you understand the routine could return <= 0 if validation fails (two modes basically, syntax fault and mx fault).
Feel free to leave a comment or send me your own version of the code!
Cheers!
