import re
data="""
Message-ID: <1608636066635.7f830.79689714@crcvmail15.nm>
Received: from 125.209.x.x (net58.219.x-x.host.lt-nn.net [91.219.x.x])
by crcvmail15.google.com with ESMTP id +844Q-zuS122aEqk5CZDZg
for <test@google.com>;
Received: from 125.209.x.x (net58.219.x-18.host.lt-nn.net [91.219.x.x])
by crcvmail15.google.com with ESMTP id +844Q-zuS122aEqk5CZDZg
for <test@google.com>;
Tue, 22 Dec 2020 11:20:58 -0000
From: "test"<from@google.com>
To: test@google.com
Subject:example email
Content-Type: text/html; charset="utf-8"
Content-Transfer-Encoding: quoted-printable
"""
fields = ['From','To','Cc','Subject','Message-ID','Date','Return-Path', 'Reply-To']
pat = fr'^({"|".join(map(re.escape, fields))})\W+(.*)'
result = dict(re.findall(pat,data, re.M))
print(result)
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