SMTP send connector SSL
Get-SendConnector | fl fqdn
Get-ExchangeCertificate | fl CertificateDomains
Get-ExchangeCertificate | fl thumbprint, services
Enable-ExchangeCertificate -Thumbprint A2AB2228777CE4539xxxxDF3F7D22A2E94326A99 -Services IMAP, POP, IIS, SMTP -DoNotRequireSSL
