HTML in DSpace messages

We like to add HTML-layout to eMail messages as send by DSpace.
Simple adding HTML-tags to one of the eMail templates as 'subscription' does not work.
I suppose we have to do some Java programming, but I have no idea where to start.
Does anyone of you has experience with HTML in DSpace eMails?

Adding HTML tags in the EMail can be done, but this requires some changes to the default EMail class.

It consists of the following changes:

• When setting the text on the actual message sent, an additional subType can be added (Check : https://github.com/DSpace/DSpace/blob/master/dspace-api/src/main/java/org/dspace/core/Email.java#L293). By default this takes a text and the charset, but has an additional "subType". Setting this to "html" enables the message to properly check for tags.
• In the "EMail" class, you could add an additional "subType" variable which defaults to "plain" for example, and can be overwritten through a setter. (I'd refrain from simply setting it to html for every email template as the checking for existing tags might break other templates and also take some extra time).
• The actual code that calls the "subscription" template can then create the mail and set the subtype properly.

• See example images for the difference between the "plain" and "html" subtype.

  "plain" subtype vs "html" subtype