I ask, because in the past I toyed with switching to using Emacs as my e-mail client, but aways got stuck on configuring the whole setup to work reliably and seamlessly.
I'm using Mu4e with 4 different mail accounts, though and it's completely seamless and easy to compose.
If you're interested, you can check out my configuration (which is written in literate org-mode so it's actually easy to read^^): https://github.com/munen/emacs.d/blob/master/configuration.o...
How's your experience with literate config, in terms of managing it? I've been meaning to switch from my mess of individual files to something like this for a time now.
Regarding literate configuration: It's been super easy, honestly. I used to have a longer init.el (formerly super long vim.rc^^). Once I wrote a short macro that converted comments into new headings in org to get me started. Then, every time I touch something, I just add a little more documentation to guide me and others for the next time. It's not more work than writing a regular init.el with comments, but the result is so much more powerful (folding->refactoring, documentation on Github, etc).
Can only recommend it, at least for Elisp.
I use OfflineIMAP to sync the two accounts to ~/Maildir/{work,personal}, then mu4e-context to switch between settings for the two.
I entirely outsource actually sending the mail to a local exim4 daemon which is configured to forward through a GMail smarthost. IMNSHO this is much better than the recommended default configuration of making Emacs actually send the mail, I don't have to worry about not having a network connection at the time, or some other transitory error with a real smtpd retrying the send if needed.
You then may need a tiny hack on top of Debian's default exim configuration to make it switch between different smtp servers / accounts depending on what address you're sending mail from. For reasons I won't go into I send E-Mail through a company-run SMTP server even though I then fetch work E-Mail from GMail.
I'll definitely consider your trick for sending e-mail - I definitely value both Emacs not hanging and also having the ability to send e-mails off-line.