On my Nexus 7 I use the stock email app for several email accounts from different providers and can send from anywhere using the PlusNet SMTP servers.
The settings I use are:
SMTP server: relay.plus.net Security Type: None (PlusNet don't support such security) Port: 587 Require Sign-in: Yes (i.e. tick the box) Username: MY PLUSNET USERNAME (same as I use for email access on my PCs) Password: MY PLUSNET PASSWORD (same as I use for email access on my PCs)
PlusNet are a bit unusual in that they let you access their SMTP servers from anywhere as long as you supply your username and password, even when you aren't connected to their broadband. AFAIK most other providers do not allow this (e.g. TalkTalk ?)
You should be aware that using this approach outbound email probably will not end up in your sent items on other machines. The way to overcome this is to BCC yourself when sending.