NOTIFY=FAILURE,DELAY: malformed address

Question

We are not able to send am email with Limilabs.Client.SMTP.Smtp class on some mail servers.

For example, with the following smtp configuration:
Outgoing server: cloud203.mxserver.ro
Port: 465
Use SSL: true

smtp.SendMessage(email);

returns the following error message in SendMessageResult:

dummy@yahoo.com NOTIFY=FAILURE,DELAY: malformed address: NOTIFY=FAILURE,DELAY may not follow dummy@yahoo.com

With this exact test case (instead of dummy@yahoo.com I use a real email address) we were able to send an email to this address using Mozilla Thunderbird email client, so I think this demonstrates the configuration is correct, and the address is also correct.
Can you please tell me what is wrong and how can I fix it?

Answer 1

It seems your SMTP server doesn't support NOTIFY parameter.
Simpy don't use it. Remove this line from your code:

smtp.Configuration.DeliveryNotification = DeliveryNotificationOptions.OnFailure |
   DeliveryNotificationOptions.Delay;

Please note that OnFailure and Delay should be the servers' default setting.