Yes, I'm using it with notmuch, and it works reasonably well. A couple of caveats: - If you want to save outgoing mail, you need to include your own mail-sending script (mine is below). This is because aerc treats the notmuch backend as read-only. - For the same reason, you can't postpone messages with the notmuch backend. - I find it a little annoying jumping between search queries. Basically, I have to type out the new query each time. The aerc notmuch backend treats notmuch queries like folders, but it instantly forgets the previous "folder" existed when you go to a new one. It probably wouldn't be too hard to fix these; if I stick with aerc I'll probably try eventually.

My mail-sending script; tested only on OpenBSD:

  #!/bin/sh
  #
  # Save a copy of an email in Sent, then send it with sendmail.
  set -e
  
  TMP=$(mktemp -d)
  cat > "$TMP/message"
  notmuch insert --folder=Sent < "$TMP/message"
  sendmail -f falsifian@falsifian.org "$@" < "$TMP/message"
  rm -r -- "$TMP"