[MlMt] S/MIME (expired) certificate handling

[Sebastian Hagedorn]

On 6 Jan 2026, at 11:38, Robert M. Münch wrote:

> Hi, I'm using S/MIME to sign/encrypt my emails. The current certificate has now expired, so I got a new one.
>
> 1. How does MM handle old emails sent to me? Are those decrypted on receive and then stored unencrypted? Does MM need to have access to the expired certificate?

The latter.

> 2. How does MM select the appropriate certificate? Do I have to delete the old one? Does MM only search for a valid one?

There a multiple ways. You can use Keychain Access to choose the valid one, or you can enter it into MailMate's Security.plist:

{
	map = (
		{
			address = "xxx at test.de";
			serial = "25 0E 3A 33 6D 11 4C 0E A2 FD F6 AD 6A 36 A5 FB";
		},
	);
}

Cheers,
Sebastian
-- 
   .:.Sebastian Hagedorn - Weyertal 121 (Gebäude 133), Zimmer 2.13.:.
                .:.IT Center University of Cologne (ITCC).:.
  .:.Universität zu Köln / Cologne University - ✆ +49-221-470-89578.:.
                .:. SIP/Webex a0620 at uni-koeln.de .:.
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