Any updates on this?

What does the certificate management interface says about your imported cert from SOGo web?

When importing a cert, SOGo apparently correctly imports it.

However, when sending a mail with the according cert, the signature of the sent message is invalid (see attached picture) and if one would enrypt the message, the receiver is unable to decrypt it.
I tried importing the cert various times on different versions of SOGo but it never worked correctly.

Oddly, the same cert works just fine when imported into Nine on Android and sent mails from there have a valid signature and working encryption (see also attached picture)

Same issue as @lekron here ... Works perfectly with other programs (eg. thunderbird) but not in SOGo... :-(

Outlook error text:
The message content may have been changed.
Signed by *** using RSA/SHA256 at 12:21:51 09/23/202020.

Any ideas?

2020-09-23 12_29_33-Test von Sogo - signiert [signed OK] - Nachricht (HTML).png (62,537 bytes)   

2020-09-23 12_29_33-Test von Sogo - signiert [signed OK] - Nachricht (HTML).png (62,537 bytes)   

Not related to the main topic of this ticket (certificate error when sending mail) but to the two previous posts (signatures broken in Outlook):

This affects MIME messages only. Pure text mails are ok.

According to RFC2046 (https://tools.ietf.org/html/rfc2046#section-5.1.1) a MIME message ends with the close delimiter (MIME boundary + "--" and optional whitespaces). A following newline and any text after it is the epilogue which is to be ignored or outright discarded.

OpenSSL signes everything you pass to it (including the epilogue) and also includes the epilogue when verifying a signature. Outlook on the other hand ignores the epilogue when verifying a signature (which sounds more standards compliant to me).

SOPE appends a CRLF to the close delimiter of MIME mails, i.e. an epilogue consisting of just "CRLF". This results in Outlook reporting broken signatures for SOGo signed MIME mails.

Fix attached.

--- sope-mime/NGMime/NGMimeMultipartBodyGenerator.m.orig	2019-12-17 20:34:06.000000000 +0000
+++ sope-mime/NGMime/NGMimeMultipartBodyGenerator.m	2020-09-25 18:50:50.850010659 +0000
@@ -206,7 +206,7 @@
   }
   [data appendBytes:"--" length:2];
   [data appendBytes:[_boundary cString] length:[_boundary length]];
-  [data appendBytes:"--\r\n" length:4];
+  [data appendBytes:"--" length:2];
   return data;
 }
 

How can I use these patch file?

You would have to compile SOPE yourself from the sources.

Btw.: Do you also get the "no error information available" message when sending a mail (the original topic of this ticket) or do you just suffer from the broken signatures in Outlook?

Okay thanks. Than I will wait that it's hopefully fixed in the next versions of sogo.
I only have the trouble with Outlook.

@ schmirl I have added your patch, thanks!

Thanks @ludovic

@lekron: Regarding the "No error information available" error message: does this error still show up and which version of SOGo are you running ATM?