[Bug]: Umlaut in sender name not shown correctly

[0xd3e]

Preflight Checklist

• I could not find a solution in the documentation, the existing issues or discussions
• I have joined the ZITADEL chat

Environment

ZITADEL Cloud

Version

v2.52.0

Database

None

Database Version

No response

Describe the problem caused by this bug

I've added our SMTP provider to our cloud instance. Our company name is "RÄUMLICH" so I've set the Sender Name to this value. Unfortunately there seems to be an issue with umlauts because my mail client shows "RÃUMLICH".

The raw email message shows this =?UTF-8?Q?R=C3=83=C2=84UMLICH=20?=.

To reproduce

1. Go to instance settings > SMT Provider
2. Click on the configured provider to edit
3. Click Continue
4. Enter a sender name that contains an umlaut
5. Click save
6. Create new user in an organization using an email address you can access
7. Check your email inbox and look at the name of the sender

Screenshots

No response

Expected behavior

Umlaut should be shown correctly

Operating System

No response

Relevant Configuration

No response

Additional Context

The PR #6637 seems to fix a similar issue for the email subject.