Is it possible to add a "HTML Body must contain" field under the Conditions?
No, it is not possible. Thanks for pointing this out, I will add it to the things pending to be added to Email Parser.
You can however write a script for this. See the advanced box in the Email Filter settings window. A bit more difficult but doable.
You can however write a script for this. See the advanced box in the Email Filter settings window. A bit more difficult but doable.