(VB.NET) GMail IMAP Authentication using OAuth2 Access Token

Demonstrates how to do IMAP OAuth2 authentication for GMail (or any other IMAP mail server supporting OAuth2 authentication). This example assumes an OAuth2 access token was previously obtained.

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' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' See Get GMail IMAP OAuth2 Access Token for Desktop App 
' for sample code showing how to obtain a GMail IMAP read/write access token.

' In this example, our access token was previously saved to the following file which contains JSON like this:
' 	{
' 	 "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
' 	 "token_type": "Bearer",
' 	 "expires_in": 3600,
' 	 "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
' 	}
' 
Dim json As New Chilkat.JsonObject
Dim success As Boolean = json.LoadFile("qa_data/tokens/_gmailFullAccess.json")
If (success <> True) Then
    Debug.WriteLine("Failed to load GMail access token file.")
    Exit Sub
End If

Dim accessToken As String = json.StringOf("access_token")

' Do OAuth2 authentication by using the access token as the password in the Login method below...
Dim imap As New Chilkat.Imap

imap.Ssl = True
imap.Port = 993

' Connect to the GMail IMAP server.
success = imap.Connect("imap.gmail.com")
If (success <> True) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


' Indicate that XOAUTH2 authentication is to be used:
imap.AuthMethod = "XOAUTH2"

' Login
' Use the email address of the GMail account that granted authorization.
success = imap.Login("user@gmail.com",accessToken)
If (success <> True) Then
    Debug.WriteLine(imap.LastErrorText)
Else
    Debug.WriteLine("Successfully authenticated with GMail IMAP using XOAUTH2!")
End If