'possible delivery' - what is it mean?

a user told me that he sent email to couple of external email address but they never received his email message. no bounce back were received by him either. i checked our mail server transmission log and found that messages were sent out but ended with the following message

Message 12345567 to abc@xyz.com received remote SMTP response 'possible delivery'.  

what is "possible delivery" mean?
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pwustConnect With a Mentor Commented:
Most probably there is a Ironport device within message flow which features "Possible Delivery".

If a message delivery times out before recipient host ackknowledges receipt of message body stream, Ironport can be set up to deem the message as "possible delivery", but still completed successfully.

Ironport's recommended setting is having this feature turned on, however, IMHO this violates RFC2821, since recipient has not yet taken over responsibility for the mail message, but Ironport claims to have transferred the message successfully with a 250 return code.

qsecofr8Author Commented:
so this message isn't returned from the remote server ? instead it is generated from our ironport device?
yes. my office use ironport
yes it is.
qsecofr8Author Commented:
thank you
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