iOS iPhone "This message has no content" or "Dieses Mail hat keinen Inhalt"

Technical assistance
#1
  • Used Zammad version: 5.3.1-1671805004.9b7729da.xenial
  • Used Zammad installation type: Package
  • Operating system: Ubuntu 16.04.7 LTS
  • Browser + version: Chrome 109.0.5414.75
  • Mail Client: e.g. iOS 16.2 iPhone 13 Pro

Expected behavior:

  • Mails sent through Zammad to a customer using iOS Mail client, should be readable.

Actual behavior:

  • Mails sent through Zammad to a customer using iOS Mail client, can not be displayed, instead show “This message has no content”. Only Mails sent to a OFFICE365 provided account can be read in iOS Mail client.

Steps to reproduce the behavior:

  • Sending a Mail through Zammad to any customer that uses iOS as Mail client. Reproduced on 4 different iphones today.
#2

The Problem still exists. Our Zammad is connected to Microsoft365 and sends the Mails through it. I updatet the whole machine and my Zammad Version is now 5.3.1-1674821848.19f3fbcd.xenial but i still have the same Problem.

#3

Problem found: We tested a signature-service (sigsync.com) and after i disconnected sigsync from microsoft365, the problems were gone.