Webmail multiple SSL certs

[stonecutter]

I have a wildcard ssl cert for the mail server but also have a client with their own wildcard ssl cert for their domain. I have imported their certificate from the other machine which hosts their website and tried to add their domain to the list of host headers in Webmail and apply their cert in IIS 7 but got a warning when trying to add the ssl binding that doing so would affect the other certificates on the web server.
How do I add other domains to the host headers for webmail and apply a different certificate without affecting the certificate being used for ME?
I want to do the same thing for the Webmail Administration but the process would be the same for Webmail, so I just need to know the correct procedure for using more than one certificate for the host headers.
Thanks.

[dedicate-it.net]

IIS7 does not support SNI which is required to host multiple SSL certificates bound to one website with multiple host headers (ie: domain1.com / domain2.com) .

IIS8+ is required for this functionality:
https://stackoverflow.com/questions/5006714/iis-7-ssl-for-multiple-sites-with-a-single-ip


Additionally, IIS7 is a part of Windows Server 2008 which is LONG past End-of-Life unless you are on ESU, which will still expire by end of 2023. Upgrade is recommended for security's sake:
https://learn.microsoft.com/en-us/lifecycle/products/internet-information-services-iis

[stonecutter]

That's what I suspected because I was able to use a wildcard cert with no problem in IIS 10. I was planning to upgrade the OS in a few months but will now do it sooner than later. Thanks for the nfo.