#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)(\r?\n)\s*\+\s*(?=\d{2}[- \/.]\d{2}[- \/.]\d{4})|\r?\n\s*\+\s*"
Local $sString = "22/03/2012 intro" & @CRLF & _
" + 22/03/2012 body" & @CRLF & _
" + more body" & @CRLF & _
""
Local $sSubst = "$1"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
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