You can add these field tags into mails using the content filtering system. There are many available tags as you can view via
http://www.code-crafters.com/abilitymai ... dtags.html as stated in the last reply. However, there aren't currently any field tags for the max mail size but there is a failure mail generated when the max mail size is exceeded in the Messages settings where you can insert the Max Mail Size manually if you want to. I'll make a note for this new field tag to try to be added in the next update.