In Microsoft Exchange You Receive the Error Delivery to the following recipients has been delayed.

To verify whether this is the cause:

1.Open Exchange System Manager.
2.Expand Servers, and then expand ServerName.
3.Expand Protocols, and then expand SMTP.
4.Expand Default SMTP Virtual Server, and then expand Queues.

Remote Delivery Queues will be displayed in retry mode (A Blue Arrow).

To view the description of the queues in retry status:

1.Right-click a queue in retry status, and then click Properties.
2.The upper status box should read, "Retry, Remote delivery".
3.The lower box should read, "The remote SMTP service rejected AUTH negotiation".

Using DNS for Delivery

By default, Anonymous access is the default setting for sending SMTP mail by using DNS to all Internet domains. To resolve this behavior:

1.F  ollow these steps to change the SMTP virtual server:
    a. Open Exchange System Manager.
    b. Expand ServerName, expand Protocols, and then expand SMTP.
    c. Right-click Default SMTP Virtual Server, and then click Properties
    d. Click the Delivery tab.
    e.    Click Outbound Security.
    f. Click to select the Anonymous access option, click OK, and then click OK again.

2. Follow these steps to change the SMTP connector:

    a. Locate, and then expand Connectors.
    b. Right-click SMTP Connector, and then click Properties
    c. Click the Advanced tab.
    d. Click the Outbound Security button.
    e. Click to select the Anonymous access option, click OK, and then click OK again.
    f. Close Exchange System Manager.