Problem with IMAP/POP outlook/office 365 (Invalid response starting char.)

I test the sample code from home with account, but I have a error message, with follow message

$exception{“Invalid response starting char.”}


Do you help me?

Hi Erick,

Unfortunately, I was unable to reproduce your issue.

Just in case, please try again with the current latest bugfix version:

If the problem remains, please send us a small Visual Studio project that reproduces your issue so that we can investigate it. You can send it to us with an email or a support ticket (see our Contact page).


Hi Erick,

Another thing you may want to check is what message your get on ImapClient.LogOutput.
For example, like this:

Using imap = New ImapClient("...")
    imap.LogOutput = Console.Out
End Using

Can you tell me what you get?


1 Like

When I debug, I get message with problems that I haven’t TLS 1.2

I solved with add this :

Const Tls12 As SslProtocols = DirectCast(&HC00, SslProtocols)

Obtained from: