Based on the results of an in-depth study, I found out that everything is fine in mail clients. The problem was precisely in the web client - SOGo.
It seems a similar problem is mentioned in . But the whole text of the letter is not displayed there, and in my case, part of the text is cut off. mailcow/mailcow-dockerized 5169
Updated from 2023-04a to 2023-04b - all the same.
For convenience, I considered the same letter: in the sent folder I see a cropped one in SOGo (the first 5 lines of text), the same letter is displayed in full in the mail client.
Should I upload screenshots and a letter in eml format here?
I will try to create an application in bugs.sogo.nu . Can I collect additional data and logs from mailcow for future diagnostics?