Posted last night from my phone, using the web browser. I’ve done this a couple times, it’s functional but the interface isn’t all that great. Set up ‘post by mail‘ today, which should be easier to compose
emails on the phone and send them. General directions are here. The one trick is when using gmail, which requires ssl for POP3, you need to specify ‘ssl://pop.gmail.com’ as the mail server and port 995.