S/MIME email certification check shows all-lowercase email address when it is mixed case
I am using Fedora Workstation 38 with Evolution and a mailbox located on Microsoft Exchange Server 2016.
$ rpm -qa | grep -i evolution | sort
evolution-3.48.4-1.fc38.x86_64
evolution-data-server-3.48.4-1.fc38.x86_64
evolution-data-server-langpacks-3.48.4-1.fc38.noarch
evolution-ews-3.48.2-1.fc38.x86_64
evolution-ews-langpacks-3.48.2-1.fc38.noarch
evolution-langpacks-3.48.4-1.fc38.noarch
I receive emails from a mailbox on the same server. My correspondent uses Microsoft Outlook 2019. The email server enforces a rule to make all email addresses use uppercase letter on first character of first and last name, i.e. "First.Last@domain.de". Evolution shows this correctly in email headers FROM and TO field.
We use S/MIME email certificates. Evolution's S/MIME certificate check always shows the email address as all-lowercase, i.e. "first.last@domain.de", which is not as expected. I noticed this several years ago. I finally took time to write a bug report.
In Evolution's mail preview window the one-line certification header is shown above the common email headers. It has a green background. It reads after being expand twice (1) click on icon on the left, 2) at "Details" click on arrow) (replace **text**
with a bold version of text):
Valid signature (first.last@domain.de)
**Digital Signature**
This message is signed and is valid meaning that it is very likely that this message is authentic.
Signer: first.last@domain.de [View Certificate]
▼ Details
Signer: <unknown> <first.last@domain.de>: Good signature
**Encryption**
This message is not encrypted. Its content may be viewed in transit across the Internet.
What does <unknown>
refer to?
When you click on [View Certificate]
a window pops up. Its title is "first.last@domain.de". Its content is:
Certificate
Identity E=First.Last@domain.de,OID...
Issuer GEANT Personal CA 4
Expires on ...
Subject
Email first.last@domain.de
...
...
[Close]
(For older certificates the Identity value was "First Last", but Subject's Email value was "first.last@domain.de" too. I guess that is due to new baseline requirements.) Decoding the base64-encoded attachment smime.p7s with https://www.base64decode.org/ I see only First.Last@domain.de.
For the same email Microsoft Outlook 2019 uses the email address in the correct mixed-case spelling. Open the email and open the signing details (in preview pane click on red seal icon), a window pops up and it reads:
Digital Signature: Valid
---
Subject: email subject line
From First Last
Signed First.Last@domain.de
The digital signature on this message is Valid and Trusted.
For more information about the certificate used to digitally sign the message, click Details. [Details...]
[x] Warn me about errors in digitally signed email before message open
[Close]
Clicking on [Details...]
a window pops up and it reads:
Message Security Properties
---
...
**Security Layers**
...
v Subject: email subject line
v Digital Signature Layer
v Signer: First.Last@domain.de
...
As far as I remember according to RFC 5321 the email address part before "@domain.de" must be checked for case.