Focus Mode for composing emails
Apps like iA writer and Markdown have a Focus Mode that only highlight the sentence you're currently typing and fade out the rest. That would be an awesome feature for composing emails:
This is an email client, not a full-blown markdown editor. I'd rather not have Airmail bloated with features
Also, syntax highlighting (highlight all verbs, nouns etc.) would be great. iAWriter Pro has this and it seems really cool!