I am not sure if this is a bug in mail.app, or a configuration I just can't find. It might also be a strange sideffect of GPGmail.

Mail.app correctly displays all e-mails on my IMAP server, except for the e-mails in my "Sent Messages" folder. In the sent messages folder it messes up åäö, in typical quoted-printable with wrong char-set fashion. They become ‰ˆ.

When looking at the source of the e-mails it seems like the header generated by mail.app is correct:

Message-Id: <>
From: 
To: 
In-Reply-To: <>
Content-Type: multipart/signed; protocol="application/pgp-signature";
    micalg=pgp-sha1; boundary="Apple-Mail-4--741321197"
X-Smtp-Server: smtp.example.com
Content-Transfer-Encoding: 7bit
Mime-Version: 1.0 (Apple Message framework v936)
Subject: Example subject
Date: Fri, 26 Mar 2010 10:14:14 +0100
References: <>
X-Pgp-Agent: GPGMail 1.2.0 (v56)

This is an OpenPGP/MIME signed message (RFC 2440 and 3156)
--Apple-Mail-4--741321197
Content-Type: text/plain; charset=ISO-8859-1; format=flowed; delsp=yes
Content-Transfer-Encoding: quoted-printable

<Text here with =E5=E4=F6>

--Apple-Mail-4--741321197
content-type: application/pgp-signature; x-mac-type=70674453;
    name=PGP.sig
content-description: This is a digitally signed message part
content-disposition: inline; filename=PGP.sig
content-transfer-encoding: 7bit

-----BEGIN PGP SIGNATURE-----
Version: GnuPG/MacGPG2 v2.0.12 (Darwin)

iEYEARECAAYFAkus62kACgkQlIRLofxhDjYnnwCcDmCXuMGsKlh3a418s12coJgn
36sAoKMdkP3+g/OMK+Ps7AbjQq4Nbqzv
=XMko
-----END PGP SIGNATURE-----

--Apple-Mail-4--741321197--

Thunderbird has no problem displaying the messages. So, how can I get mail.app to use the correct charset?