Using SSL encryption for sending emails

[FlashFlyyy]

When I set 'enableSsl' to 'true' I get the following errors,

[12:33:56] System.IO.IOException: The handshake failed due to an unexpected packet format.
   at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
   at System.Net.Security.SslStream.AuthenticateAsClient(String targetHost, X509CertificateCollection clientCertificates, SslProtocols enabledSslProtocols, Boolean checkCertificateRevocation)
   at MailKit.Net.Smtp.SmtpClien*****nnect(Uri uri, CancellationToken cancellationToken)
   at MailKit.MailService.Connect(String hostName, Int32 port, Boolean useSsl, CancellationToken cancellationToken)

When I set 'enableSsl' to 'false' I get no errors and emails are sent successfully.
Am I using a port that does not have 'ssl' enabled? If so then how do I fix this?

Is it a big flaw if I don't use ssl to encrypt emails?

[SeXZeFPS]

When I set 'enableSsl' to 'true' I get the following errors,

[12:33:56] System.IO.IOException: The handshake failed due to an unexpected packet format.
   at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
   at System.Net.Security.SslStream.AuthenticateAsClient(String targetHost, X509CertificateCollection clientCertificates, SslProtocols enabledSslProtocols, Boolean checkCertificateRevocation)
   at MailKit.Net.Smtp.SmtpClien*****nnect(Uri uri, CancellationToken cancellationToken)
   at MailKit.MailService.Connect(String hostName, Int32 port, Boolean useSsl, CancellationToken cancellationToken)

When I set 'enableSsl' to 'false' I get no errors and emails are sent successfully.
Am I using a port that does not have 'ssl' enabled? If so then how do I fix this?

Is it a big flaw if I don't use ssl to encrypt emails?

What port is it running on?

[FlashFlyyy]

I think 587 (unless this is the gmail server port and not the one I am sending from)

How would I check?