Mailkit Authenticate to Imap fails

问题:

I'm trying to use MimeKit and MailKit to fetch e-mail from inbox.
But the logon to the mail server Imap does not work.
I'm using port 993 with ssl.
I have tried to connect/LOGIN/FETCH on port 143 with Telnet and it works.
I have tried to connect/LOGIN/FETCH on port 993 with Openssl and it works.
Mailkit v.1.4.2.1

KODE:

     using (var client = new ImapClient(new ProtocolLogger("imap.log")))         {             try             {                 client.Connect(server, this.port, true);                 client.AuthenticationMechanisms.Remove("XOAUTH2");                                     client.Authenticate(user, password);                 var inbox = client.Inbox;                 inbox.Open(FolderAccess.ReadWrite);                  if (inbox.Count > 0)                 {                     var range = Enumerable.Range(0, inbox.Count).ToArray();                     inbox.AddFlags(range, MessageFlags.Deleted, false);                     inbox.Expunge();                 }                 client.Disconnect(true);             }             catch (AuthenticationException e)             {                 throw e;             }         } 

IMAP.LOG:

    Connected to imaps://xxxx.xxx.xx:993/     S: * OK The Microsoft Exchange IMAP4 service is ready.             C: A00000000 CAPABILITY     S: * CAPABILITY IMAP4 IMAP4rev1 AUTH=PLAIN AUTH=NTLM AUTH=GSSAPI UIDPLUS MOVE ID CHILDREN IDLE NAMESPACE LITERAL+     S: A00000000 OK CAPABILITY completed.     C: A00000001 AUTHENTICATE NTLM     S: +     C: TlRMTVNTUAABAAAABwIIAAAAAAAgAAAAAAAAACAAAAA=     S: +     TlRMTVNTUAACAAAABgAGADgAAAAFAokCETTDB74D2YsAAAAAAAAAAKIAogA+AAAABgLwIwAAAA9LAE0ARAACAAYASwBNAEQAAQAUAEsATQBEAEUAWABDADIAMAAwADYABAAaAGkAbgB0AGUAcgBuAC4AawBtAGQALgBkAGsAAwAwAEsATQBEAEUAWABDADIAMAAwADYALgBpAG4AdABlAHIAbgAuAGsAbQBkAC4AZABrAAUAGgBpAG4AdABlAHIAbgAuAGsAbQBkAC4AZABrAAcACAA8TRLTaRLSAQAAAAA=     C: TlRMTVNTUAADAAAAGAAYAFYAAAAYABgAbgAAAAAAAABIAAAADgAOAEgAAAAAAAAAVgAAAAAAAACGAAAAAYIIAgoAWikAAAAPaQBvAG0AdABlAHMAdAA6stwc8LXYfAAAAAAAAAAAAAAAAAAAAAC5L0RCGGq9hCGwriyfURwGscjNCDTBeSA=     S: A00000001 NO AUTHENTICATE failed.     C: A00000002 AUTHENTICATE PLAIN     S: +     C: XXXXXXXXXX     S: A00000002 NO AUTHENTICATE failed.     C: A00000003 LOGIN xxxxxxxxx xxxxxxxx     S: A00000003 NO Server Unavailable. 15     S: * BYE Connection closed. 14A 

Exception:

    AuthenticationException: “Authentication failed.”     at MailKit.Net.Imap.ImapClient.Authenticate(Encoding encoding,    ICredentials credentials, CancellationToken cancellationToken)        at MailKit.MailService.Authenticate(String userName, String password,    CancellationToken cancellationToken) 

回答1:

There is/was a bug in AUTHENTICATE NTLM authentication which is the first authentication mechanism that MailKit tried in your case. Unfortunately, there's also a bug(?) in Exchange in that when NTLM auth fails, it automatically seems to deny AUTHENTICATE PLAIN which is what MailKit falls back to trying.

As a workaround, disable NTLM authentication in MailKit by doing this:

client.AuthenticationMechanisms.Remove ("NTLM"); 

The resulting code should look like this:

using (var client = new ImapClient(new ProtocolLogger("imap.log"))) {     try     {         client.Connect(server, this.port, true);         client.AuthenticationMechanisms.Remove("XOAUTH2");         client.AuthenticationMechanisms.Remove("NTLM");         client.Authenticate(user, password);         var inbox = client.Inbox;         inbox.Open(FolderAccess.ReadWrite);          if (inbox.Count > 0)         {             var range = Enumerable.Range(0, inbox.Count).ToArray();             inbox.AddFlags(range, MessageFlags.Deleted, false);             inbox.Expunge();         }         client.Disconnect(true);     }     catch (AuthenticationException e)     {         throw e;     } } 

文章来源: Mailkit Authenticate to Imap fails