[horde] Change Image Share calendar

[Álvaro Javier Gasco Fernández]

Good Morning.

My name is Alvaro and i have an issue with my horde app. It is a request
more than an issue.
When i share a calendar with somebody in my business, he receives an email
with the subject (Access permissions) and the body contains an image (a
calendar with 2 rows). I would like to change this image and put my
business logo.

Thanks.