Yes, 1.7+ has a known bug when the same name is used for user domain and mail domain. So the Software Center update isn’t shown.
It’s possible to update manually, see Relay error after update mail node to 1.7.0 - #14 by mrmarkuz
If something’s not working, it’s possible to revert from 1.7.1 to 1.6.4, see Relay error after update mail node to 1.7.0 - #11 by davidep