CDO.Message delivery notification failed - email

Question

Here is my environment: Windows Server 2003, Microsoft Access 2003, Microsoft VB 6.5
Trying to send email from Access using CDO.Message. Here is the portion of my code:
Private Sub btnTestEmail_Click()
On Error GoTo SendMail_Error:
Dim Mailmsg As Object
Dim mailconf As Object
Dim McFields As Object
Dim strSchemas As String
Set Mailmsg = CreateObject("CDO.Message")
Set mailconf = CreateObject("CDO.Configuration")
Set McFields = mailconf.Fields
strSchemas = "http://schemas.microsoft.com/cdo/configuration/"
With McFields
.Item(strSchemas & "sendusing") = 2
.Item(strSchemas & "smtpserver") = "smtp.gmail.com"
.Item(strSchemas & "smtpserverport") = 465
.Item(strSchemas & "smtpauthenticate") = 1
.Item(strSchemas & "sendusername") = "my_email#gmail.com"
.Item(strSchemas & "sendpassword") = "my_gmail_password"
.Item(strSchemas & "smtpconnectiontimeout") = 60
.Item(strSchemas & "smtpusessl") = 1
.Update
End With
Set Mailmsg.Configuration = mailconf
With Mailmsg
.TextBody = "Test email body text"
.Subject = "Test email subject"
.To = "target_email#gmail.com"
.from = "my_email#gmail.com"
'.AddAttachment "D:\test.pdf"
.Fields("urn:schemas:mailheader:disposition-notification-to") = "my_email#gmail.com"
.Fields("urn:schemas:mailheader:return-receipt-to") = "my_email#gmail.com"
' Set delivery status notification (DSN)
' Name Value Description
' cdoDSNDefault 0 No DSN commands are issued.
' cdoDSNNever 1 No DSN commands are issued.
' cdoDSNFailure 2 Return a DSN if delivery fails.
' cdoDSNSuccess 4 Return a DSN if delivery succeeds.
' cdoDSNDelay 8 Return a DSN if delivery is delayed.
' cdoDSNSuccessFailOrDelay 14 Return a DSN if delivery succeeds, fails, or is
.DSNOptions = 0
.Fields.Update
.Send
End With
MsgBox "Message Sent", vbOKOnly
Set Mailmsg = Nothing
Set mailconf = Nothing
Set McFields = Nothing
Exit Sub
SendMail_Error:
MsgBox Err.Description, vbOKOnly
End Sub
With DSNOptions = 0 works great but I would like to get delivery notification (not read notification).
If I set DSNOptions to any allowed non-zero value the email doesn't even arrives to the target email and I don't get any notification to my email.
Strange thing if I set unexisting target email (on purpose) I get delivery unsuccessful notification even with DSNOptions = 0.
Am I missing something in the code? Found on multiple other web site people claims this code works but using other smtp servers. Any help appreciated.