Mail not found, but whole source available

[mat-m]

Steps to reproduce

1. I click on an email in the list (from 2 days ago, unread), and I get a "Not Found" error instead of the body, but headers are shown
2. When I click the View Source in the mail headers, I get the full HTML body of the email

Expected behavior

Display the email body

Actual behavior

Error message in the page.

Also, in the logs, I have this error:

Exception
Call to a member function getEmail() on null in file '/var/www/html/custom_apps/mail/lib/Service/PhishingDetection/PhishingDetectionService.php' line 34

Mail app version

4.0.2

Nextcloud version

30.0.0

Mailserver or service

https://www.laposte.net/accueil

Operating system

Windows

PHP engine version

None

Nextcloud memory caching

No response

Web server

None

Database

None

Additional info

NC deployed through docker

[ChristophWurst]

Dear @mat-m,
thank you very much for your report.
It seems there are some missing null checks in the phishing detection feature. Here's a patch: #10371.
I was not able to verify the changes myself, as the code paths only run for certain messages. I'd be happy if you can help test the changes.
See https://docs.nextcloud.com/server/30/admin_manual/issues/applying_patch.html#patching-apps for assistance.