I want to change the default XHTML editor in EPiMail tabs, is there a possibility to do so?
I have never used EPiMail but since it's based on EPiServer I would guess that you have some epimail pagetypes in admin mode that you can change?
The editor is not designed to be pluggable. Maybe you could replace it by overriding the UI files (using the mapping virtual path provider) but it could prove very difficult.
I think you can assign a page in EPiServer CMS to be responsible for the content of the mail and then you get the editor there. In fact, I think that the mail editor in EPIServer mail has been thrown out in EPiServer 7 and that this is the only alternative if you want to have html content.
Excellent suggestion Linus!
The exact request was for changing the editor, but I guess a dedicated page will do the job. 10x Linus.