Redmine

When you create issues via email, the subject of the created issue may be broken if the subject field in the original email is split into multiple lines like the following.

Date: Mon, 13 May 2019 13:39:29 +0900
Message-ID: <CALXUZfgwpW-hizEabSAjjkykQGV6-V6bwKu693Cr7cDH6DR7pQ@mail.gmail.com>
Subject: =?utf-8?B?zrHOss6zzrTOtc62zrfOuM65zrrOu868zr3Ovs6/z4DPgc+Cz4PPhM+Fz4bP?=
        =?utf-8?B?h8+Iz4k=?=
From: <foo@example.com>
To: <baz@example.com>
Content-Type: text/plain

Split bytes subject.

The subject should be decoded like this:

αβγδεζηθικλμνξοπρςστυφχψω

But the subject of the created issue will be the following:

αβγδεζηθικλμνξοπρςστυφ��ψω

This is due to the bug of mail gem (I tested in 2.7.1).

irb(main):001:0> puts Mail.read('/tmp/split-bytes-subject.eml').subject
αβγδεζηθικλμνξοπρςστυφ��ψω
=> nil

The subject is not split at the boundary between characters but in the middle of bytes that composes a character and mail gem that parses emails does not properly handle such emails. The first line of the decoded subject field is "αβγδεζηθικλμνξοπρςστυφ\xCF" and the second line is "\x87ψω". The character "χ" is consists of two bytes 0xCF and 0x87. These two bytes span two lines. mail gem cannot handle such cases.