Mail2000 信件內文採用Base64編碼,因此編譯過的信件會比原信(含附件檔案)大1.3倍左右,


Content-Transfer-Encoding: base64

From:    <bryson@m2ktrial.openfind.com.tw>
Date: Wed, 14 Nov 2018 02:00:01 +0000 (UTC)
Subject: =?utf-8?B?5o6I5qyK5Y2z5bCH5Yiw5pyf6YCa55+l77yaIA==?=
  =?utf-8?B?6Ieq5YuV5pu05paw5Yqf6IO9ICA=?=
MIME-Version: 1.0
Content-Type: multipart/related;
  boundary="---UGG.X+Yrj+abHttn4n+KoOAl8),"

This is a multi-part message in MIME format.

-----UGG.X+Yrj+abHttn4n+KoOAl8),
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: base64
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舉例:一封信件僅幾個文字,搭配1.12MB的附件,經過 base64 編碼後的信件檔案大小為1.53MB,

因此建議在設定單封信件大小上限時,需考慮加大1.3倍左右上限。


另可參考此篇郵件上限設定