Broken invitation email for 18.04

We recently upgraded a self hosted Nextcloud to 18.04 and while everything work fine, the invitation email messages sent upon creating a calendar appointment are completely messed up.

This only happens if the appointment is generated inside Nextcloud; when creating an appointment from a Caldav-connected Thunderbird / iOS calendar the message is fine. Anyone experienced the same?

What do you mean? How are they broken?

Thanks! Iā€™m including an image with the rendering on Thundebird, same in iPhone anyway. Willing to share the message source if useful.

calendar

Thanks! Could you please open an issue on https://github.com/nextcloud/server with all required information and the message source (with personal information filtered)?