EmailReplyParser - php библиотека для распарсивания простых текстовых писем
Пример
https://github.com/willdurand/EmailReplyParser
<?php
use EmailReplyParser\Parser\EmailParser;
$email = (new EmailParser())->parse($emailContent);
$fragment = current($email->getFragments());
$fragment->getContent();
$fragment->isSignature();
$fragment->isQuoted();
$fragment->isHidden();
$fragment->isEmpty();
$email = \EmailReplyParser\EmailReplyParser::read($emailContent);
$visibleText = \EmailReplyParser\EmailReplyParser::parseReply($emailContent);
https://github.com/willdurand/EmailReplyParser