#include <StringConstants.au3> ; to declare the Constants of StringRegExp
#include <Array.au3> ; UDF needed for _ArrayDisplay and _ArrayConcatenate
Local $sRegex = "(?m)(?:^(?=.*sm-mta)|\G(?!^)).*?@\K[^\s>]+"
Local $sString = "Aug 15 00:01:06 **** sm-mta*** to=<user1@gmail.com>,<user2@yahoo.com>,user3@aol.com, some_more_stuff" & @CRLF & _
"Aug 16 13:16:09 **** sendmail*** to=<user4@yahoo.com>, some_more_stuff" & @CRLF & _
"Aug 17 11:14:48 **** sm-mta*** to=<user5@gmail.com>,<user6@gmail.com>, some_more_stuff"
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