But I wish I also could make a http instead of my email
Do you mean HTML? http is the way the whole web works – except highly secure parts that use https.
I haven’t checked, but I don’t think there is anything stopping you from using HTML for kiwitrees automated mail responses. Their contents are just translatable language texts, so you can translate them either permanently or with a custom language file, to include the raw HTML tags you want.
You might also need to configure kiwitrees mail to use SMTP, but that is also just a configuration option. Edit: not required.
But are you referring to automated emails ( edit approval notifications and user registration notifications) or the contact links? I expect the contact links could include a WYSIWYG editor if your kiwitrees is configured to use it. Or you can simply include the raw html tags.