One of my servers has started to have problems out of no where. There is mainly one domain that is having the issues. Restoring backups do not fix it. The accounts are getting errors when trying to send and receive mail, but on my client which is outlook 2014 I have no errors. They have errors with windows live mail, and older outlooks. Also webmail is messed up. I can login to the webmail portal, but none of the clients there work. They either give an error of login failed or cannot connect to storage server. I have ran upnp --force, updated the server. I have restored from backups. I have looked online and found no solutions that work. It seems like it started after the server updated but my other server also updated and that one is working fine. This is not a network issue either as the problem happens when on the same LAN as server. Does anyone have any ideas?