I have a user with several domains, and one of these domains has an SSL certificate.
So, domain-a.com has a certficiate, and domain-b.com and domain-c.com does not have a certificate.
It works perfectly on domain-a.com (https://domain-a.com), and has no certificate issues.
However, when I for example add mail.domain-b.com as an IMAP server, and my mail program tries using SSL, i
I have 3 websites: aaa.my-domain.com, bbb.my-domain.com and ccc.my-domain.com all using a single wildcard certificate *.my-domain.com on IIS 7.5 Windows Server 2008R2 64-bit.
I have two SSL certificate one for *.sub.domain.com and one for *.domain.com.
I don't have issues with domain level wildcard certificate.