Yes very often. This is what I did:
I have tried different/alternative server configurations, different ports, Firewall settings, SSL on/off, imported settings via TimeMachine backup, have set a VM with a upgraded Mavericks and one clean install Mavericks - just to test the Mail settings over and over again as I really DO need it to work.
Strange thing is that everything worked perfectly fine until Mavericks and still works on ML. And now your suggestion with the Keychain, deleting the entrys, re-entering them and so one. Added Accounts via Mail and via System preferences.. nothing works.
Only thing that 'worked' was adding the same account as POP (ssl & port 110). On every other device (iPhone, iPad, MBP2012) everything works perfect.
Update:
Every IMAP setting gives me this:
