Please suggest how we can verify that email address is TLS enabled or not using your webservice.
Email address and TLS are two separate things.
Email address represents mailbox on the server.
TLS is a protocol that secures connection to the server.
Generally to connect to the server you need to know server address, port, and if TLS/SSL is used explicitly:
From a DNS perspective you have SRV DNS records which allow the use of DNS for publishing services and service discovery.
If you are looking for some more advanced auto-configuration feature:
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