- Check that the user has "Access this computer from a network" and "Log on locally" selected.
- Make sure that the account used by IIS has "Log on locally" and "Access this computer from the network" permissions.
- Confirm that IIS is configured to allow anonymous access.
- Verify the user has "read" permissions to the EXCHSRVRWEBDATA folder and "change" permissions to the EXCHSRVRWEBTEMP folder.
After that, if you are still having problems connecting, you may want to change the authentication type to "Basic." Also, try to log in the user from inside the network to narrow down your issue.
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