Hey there,
I was just trying to do this today, and after much searching around managed to figure it out. Leeds ISS doesn't seem to give specific instructions for generic IMAP accounts, but piecing together some other stuff, I came up with this setup that seems to be working for me -
go to add "other" account in the mail settings and enter the following:
Name: your name
Address: username@leeds.ac.uk
Description: whater you want
Incoming Mail Server -
Host Name: username.imap.leeds.ac.uk
User Name: username
Password: yourpassword
Outgoing Mail Server -
Host Name: smtps.leeds.ac.uk
enter your username and password here as well
Click save. For me, it worked for a little bit then I got a popup saying "SSL did not work, would you like to try turning SSL off?" I clicked yes, it worked for a little while longer, then went through.
The Leeds mail now shows up under the mail app, and I have been able to send and receive mail.
Hope it works for you!