Internal Server Error (500) in DeskApp and WebApp displaying a Mail (from Lotus Notes) with Signiture

Hello,
Every time I send a mail from business (Lotus Notes) to my Kopano Server (Univention) I get a Server Error (500) (Desk App and Web App). Attached the Mail (saved from Thunderbird). All other mails are received correct.
My Installation is on Univention 4.3-0 errata12 and the Kopana Versions are:
WebApp: 3.4.2.1108+36.1
Kopano Core: 8.4.5.0
Z-Push: 2.3.8+0-0
With very much help from the Kopano forum I figured out the following solution:
Install php7.0-curl (apt-get install php7.0-curl) and php-bcmath (apt-get install php-bcmath) and add the line extension=curl.so to /etc/php5/apache2/php.ini (I don’t now, if this is necessary). Restart the server and the error messages are gone.
Maybe add this to the install routine
Regards
Stephan Geberl

Not quite sure yet if it will fix the issue, but I’ve now added explicit php7 dependencies to the 4.3 integration package https://stash.z-hub.io/projects/K4U/repos/kopano4ucs/commits/b047bc2071f9bb47d57644dae00fb9ad2ad51e41