A number of users (my manager included) use Office 2010 x64 due to an enormous spreadsheet that requires more cells than the 32 bit version allows, all other users are on 32 bit versions of Office. This did not/does not cause any issues while their Exchange accounts are on Exchange 2007. As soon as these accounts are migrated to Exchange 2013 they see issues every morning (they generally leave their machines logged in overnight) or after an extended period away from their machines
The issue is that they have to close and reopen Outlook, if they do not do this they are unable to send or receive email and any meeting reminders do not respond to being actioned, until they do this they receive errors about server not being available. The Exchange 2007 setup (done before my time here) uses basic authentication whereas the 2013 setup uses NTLM. Users on 32 bit mail clients do not see this on either 2007 or 2013, it only seems to affect users on 64 bit Outlook, and only after they migrate to Exchange 2013.
We have tried setting the same users up on virtual machines using 32 bit Office, no problem seen. A full rebuild of one of these machines, still using Office x64, gave the same issues again. Configuring a different user account still on Exchange 2007 on the same machine gave no issues whatsoever.
Is this a known issue and is there a hotfix for NTLM authentication/Outlook x64?