We plan to support DKIM for custom domains, but can not give a target date yet. It has been added to our Roadmap: https://github.com/tutao/tutanota/milestone/8.Anonymous supported this idea ·Anonymous commented
Any update on this? This is why an easily accessible roadmap is needed for the Tutanota website. It's too hard to search the Tuta forum and Github to find out what features are actually coming.