I forgot to add some more info:
I found in www/plugins/plugins/core.mailer/layout/en.html or www/plugins/plugins/core.mailer/layout/en.txt that there is no placeholder or anything like a string, what could be replaced to a link. Is this correct?
The en.txt file looks like
My Server Filesharing
An My Server user is sharing a file with you, to download the corresponding file, click the link below:
This email was sent to you by My Server filesharing tool.
Hi,
your issue is weird the en.txt should be looking like this :
AJXP_MAIL_SUBJECT
AJXP_MAIL_BODY
-------------------
This email was sent to you by Pydio, open source file sharing software for the Enterprise.
Learn more on https://pydio.com/