#include <StringConstants.au3> ; to declare the Constants of StringRegExp
#include <Array.au3> ; UDF needed for _ArrayDisplay and _ArrayConcatenate
Local $sRegex = "(?m)(^|\s)[A-Za-z0-9][A-Za-z0-9._-]*@[A-Za-z0-9]+(\s|$)|(^|\s)[A-Za-z0-9][A-Za-z0-9._-]*@[A-Za-z0-9]+\.[A-Za-z]+(\s|$)|(^|\s)[A-Za-z0-9][A-Za-z0-9._-]*@[A-Za-z0-9]+\.[A-Za-z]+\.[A-Za-z]+(\s|$)"
Local $sString = " is exactly it! Only a dot can appear after an email (not before). And the email 'username' cant be finished with non-alphanumerical characters (so .stack_@gmail.com is invalid and so is stack.@gmail.com or stack@_gmail.com). The other relevant thing is that emails can have zero or more domains, so: stack@gmail or stack@gmail.com or stack@gmail.com.br are all valid"
Local $aArray = StringRegExp($sString, $sRegex, $STR_REGEXPARRAYGLOBALFULLMATCH)
Local $aFullArray[0]
For $i = 0 To UBound($aArray) -1
_ArrayConcatenate($aFullArray, $aArray[$i])
Next
$aArray = $aFullArray
; Present the entire match result
_ArrayDisplay($aArray, "Result")
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm