Server settings should look like:

If you want to use ssl - then you should use following settings:

for imap (select ssl/tls)

for smtp (select ssl/tls)

To connect to our webmail - open https://zimbra.brainity.com

for every domain other than brainity.com you have to use full address to login:

A complete Documentation for Zimbra can be found at: Zimbra 8.x user documentation