Tried to read a line. Only ” received.

MailForWindowsStore.dll

If you are using MailForWindowsStore.dll: Connect and ConnectSSL methods are asynchronous. You must use await ConnectSSL and await Connect:

// C#

using(Imap imap = new Imap())
{
    await client.ConnectSSL("imap.example.com");
    await client.UseBestLoginAsync("user", "password");
    // ...
}   

' VB.NET

Using imap As New Imap()
    Await client.ConnectSSL("imap.example.com")
    Await client.UseBestLoginAsync("user", "password")
    ' ...
End Using

Please make sure that you have disabled antivirus and firewall software or that you have configured it correctly.

Mail.dll

If you are using Mail.dll:

Please make sure that you have disabled antivirus and firewall software or that you have configured it correctly. This includes Windows Defender – especially if you use SMTP client.

In most cases this error means that the connection was interrupted. It was lost, the server disconnected or your antivirus/firewall cut the connection.

In technical terms, it means exactly what the exception’s message says: component tried to read a line (ending with CRLF), the line was expected in accordance to the protocol in use, but it has not been received during the specified period.

On extremely slow networks you may increase timeout values: ReceiveTimeout and SendTimeout.

In most cases you’ll need to connect again.