Having a real problem with fixing an issue.
The situation is, that every time the user closes and reopens outlook, it prompts for credentials.
I have so far done the following;
Removed credentials from vault,
Gone onto mail, email accounts, change and then more settings, and made sure the "always prompt for log on credentials" box isn't ticked,
Removed and re added the profile,
Reset the password,
Changed proxy settings from NTLM authentication to basic.
When I changed the proxy settings as above it worked and I would re open and close outlook and it wouldn't prompt for a password,. However when the user logged off and came back to his computer this morning, those settings had reverted back..