This failure occurs because the Exchange 2010 Setup program
creates a self-signed x.509 certificate for the server whose FQDN includes an
underscore character ( _ ). However, X.509 rules indicate that the underscore
character ( _ ) is not valid in X.509 certificate. The setup failure occurs in
the Tlscertificateinfo.cs file, which throws the following argument exception:
(Microsoft.Exchange.Net.NetException.InvalidFQDN(name),
"subjectAlternativeNames")
This failure occurs because the installation program does not
find any valid DNS names in the
Subject Alternative Name field
of the self-signed x.509 certificate.