When sending S/MIME signed Mails from Aqua Mail, the main Date header is generated correctly, but an additional, Non-standard Header is generated in the multipart/mixed part.

Here a snipped of the relevant source:

[more headers]
Date: Wed, 23 Apr 2025 09:48:35 +0200
Message-ID: <[email protected]>
User-Agent: AquaMail/1.55.0 (build: 105500548)
Subject: Nachricht mit Weiterleitung
MIME-Version: 1.0
Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha256; 
	boundary="SPB_1745394517200"
X-Last-TLS-Session-Version: TLSv1.3

--SPB_1745394517200
Date: Mi., 23 Apr. 2025 09:48:37 +0200 (MESZ)
Content-Type: multipart/mixed; boundary="196619ebf265dae284bbd15438"

[content]

The Date string "Mi., 23 Apr. 2025 09:48:37 +0200 (MESZ)" doesn’t seem to follow a standard and results in a InvalidMessageDateException from Header::parseDate when trying to parse the message. It’s a bit frustrating since the date which produces the error is pretty useless anyway, but prevents parsing the message completely. (Edit: I discovered the fallback date option which probably remedies that. Haven’t tested it though because I already fixed the bug)

Interestingly, the date format is very similar to the one in #198, but without the part after the slash. It should be easily fixable since the part after the slash isn’t used anyway. See the fix in my PR #575.