PLANET CS-2001 - Manual (Page 455)

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Step 2. Go to Mail Security > Configuration > Queued Mail to obtain the
delivery status.
 A symbol, under the Reason column, indicates an email is being
processed (delivered). （Figure 12-44 Figure 12-45）
 Factors that caused failed deliveries are obtainable and the email can
be resent by clicking Resend.
 Emails in the queue will be periodically resent until the delivery is
successful or the Max. lifetime of Queued Mail has been exceeded.
 To stop queued emails from delivery, tick the corresponding
checkboxes then click (or click
simply to remove them all).
Figure 12-44 Emails Being Processed
Figure 12-45 A Failed Delivery