Subject that ends with =?utf-8?Q?UTF-8?= =?utf-8?B?LCA4NSBvciBBMCBlLmcuOiDP?=

[Kenichi Asai]

Thank you all for considering this issue.

> * After you finish the above steps, what happens if you edit the email again
> in vim?  Does the 加 show up at the end of the subject in vim the second time?

No.  In vim, the character becomes ?? (two question marks).

> * With your original steps, what does the email look like if you send directly
> after returning from vim?

The replacement character is sent as seen in Bastian's e-mail:

Date: Tue, 2 Aug 2022 12:39:06 +0200
From: Bastian <bastian-muttuser at t6l.de>
To: mutt-users at mutt.org
Subject: Re: Subject that ends with UTF-8, 85 or A0 ��

(I am not quite sure why there are two replacement characters here
instead of one.)

> Would you mind sending me an email so I can take a look?

This e-mail has υ at the end of Subject.  I will send it out.

> * Does the problem occur if you use a different editor?

Let me come back to this later.  I need to send this e-mail out to try
a different editor.

> * In the step:
>   "- enter some e-mail address and a subject."
> if instead, you put a 加 at the end of the subject here, before running vim,
> does 加 show up in vim?

Yes.

> If you then don't modify the subject while still in
> vim, does it show up in Mutt?

No.  It becomes the replacement character.

-- 
Kenichi Asai