WHAT I HAVE: Visual Basic 2019, .NET 4.6.1, WinForms MY PROBLEM: I am using SmtpClient to send emails, and the documentation says that if EnableSsl is True when the server doesn't advertise StartTLS , an SmtpException is thrown. I'd like to handle that scenario intelligently. What is the StatusCode property value for when a send fails for that specific reason? The help info is a little ambiguous on that. Better yet, is there a way to determine in advance whether a server supports StartTLS and therefore preempt this kind of Smtp exception by setting EnableSsl accordingly? Please answer both questions ASAP. I'd prefer it in VB.NET, and as simple as possible. (That's what the "S" in SMTP stands for, after all!)

How do I determine if an SMTP server "advertises" StartTLS?

Robert Gustafson 606

WHAT I HAVE:
Visual Basic 2019, .NET 4.6.1, WinForms

MY PROBLEM:
I am using SmtpClient to send emails, and the documentation says that if EnableSsl is True when the server doesn't advertise StartTLS, an SmtpException is thrown. I'd like to handle that scenario intelligently.

What is the StatusCode property value for when a send fails for that specific reason? The help info is a little ambiguous on that.
Better yet, is there a way to determine in advance whether a server supports StartTLS and therefore preempt this kind of Smtp exception by setting EnableSsl accordingly?

Please answer both questions ASAP. I'd prefer it in VB.NET, and as simple as possible. (That's what the "S" in SMTP stands for, after all!)

Xingyu Zhao-MSFT 5,366 Reputation points

2021-01-22T01:28:59.827+00:00

Hi @Robert Gustafson ,

The help info is a little ambiguous on that.

You can consider reporting your problem in MicrosoftDocs/feedback.

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How do I determine if an SMTP server "advertises" StartTLS?

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