We moved from an internal AD integrated Exchange 2010 environment to an external hosted Exchange 2010.  Prior to the move credentials were passed through and never needed.  Since the move a large number of Outlook clients have not been storing credentials correctly.  The credentials show up in the windows credential manager with "Logon Session" persistence which means they disappear after the next logoff or restart.  The option to remember credentials is checked when Outlook prompts the user.  Client machines are Windows 7 SP1 x64.  For Outlook 2010 14.0.7015.1000 I did not find a fix.  A workaround I've come up with on Outlook 2013 15.0.4569.1506 is to manually recreate each of the credential manager entries created by Outlook via "add a generic credential", which then stores them with "Enterprise" persistence which keeps the info across logoffs/restarts.  This solves the problem until the password expiration hits in 90 days at which point the new info has to be reentered into the credential manager.  These are the three generic credentials entries I am manually typing into the credential manager including the parentheses character for character, with the user's full email address as username in each case to gain enterprise persistence:

Internet or network address: MS.Outlook.15:username@domain.com:PUT

Internet or network address: username@domain.com (Windows Identity)

Internet or network address: external.exchange.server.net

local autodiscover override in use -

[HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\AutoDiscover]
"domain.com"="\\\\domain.com\\sysvol\\domain.com\\scripts\\autodiscover.xml"
"PreferLocalXML"=dword:00000001
"ExcludeHttpsAutodiscoverDomain"=dword:00000001
"ExcludeHttpsRootDomain"=dword:00000001
"ExcludeScpLookup"=dword:00000001
"ExcludeSrvRecord"=dword:00000001

[HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\AutoDiscover\RedirectServers]
"external.exchange.server.net"=hex(0):

Why is enterprise persistence not happening automatically when the user checks the option to remember the credentials at an Outlook prompt?