Wrong URL-Link in Mail

[Felix-C]

Steps to reproduce

Create a new User on https://cloud.zonentalk.de/

Expected behaviour

1. System sends internal Server Name as link in mails

Actual behaviour

Tell us what happens instead

Server configuration

Operating system:
on Univention Server

Web server:
Apache

Database:
MySQL
PHP version:
7
ownCloud version: (see ownCloud admin page)
10.2.1.4
Where did you install ownCloud from:
Univention
Signing status (ownCloud 9.0 and above):

Login as admin user into your ownCloud and access 
http://example.com/index.php/settings/integrity/failed 
paste the results here.
``No errors have been found.`

**List of activated apps:**

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your ownCloud installation folder
`
Could not open input file: occ
``

The content of config/config.php:

If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your ownCloud installation folder

or 

Insert your config.php content here
(Without the database password, passwordsalt and secret)

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/...

Client configuration

Browser:

Operating system:

Logs

ownCloud log (data/owncloud.log)

Insert your ownCloud log here

Browser log

Insert your browser log here, this could for example include:

a) The javascript console log
b) The network log 
c) ...

[AlexAndBear]

Closed via #333