$re = '/^From:\s*(\S+)$/m';
$str = 'Sent: Tue Mar 05 15:42:11 IST 2019
From: xtest@xyz.co.in
To: akm@xyz.com
Subject: Re: Foausrnisfseur invadlide (030000000000:3143)
Message:
----------------------------
Sent: Tue Mar 05 15:40:51 IST 2019
From: ytest@xyz.com
To: bpcla@xpanxion.com
Subject: Foausrnisfseur invadlide (O4562000888885456:3143)
Message:
This is not right please correct
Termes de paiement Foausrnisfseur non spécifiés
impact potentiel: 3 000,00
You should write From field with abc@xyz.com
and not From: field with abc@xyz.com in the column
Date détecté: 2019-02-26 12:55:03
---- Please do not delete or modify this line. (2423000000000149:3143) ----
-------------------------
Sent: Tue Mar 05 15:40:51 IST 2019
From: ytest@xyz.co.in
To: bpcla@xpanxion.com
Subject: Foausrnisfseur invadlide (O4562000888885456:3143)';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
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 PHP, please visit: http://php.net/manual/en/ref.pcre.php