The Server responded:501 mail not accepted from blacklisted IP add

[realmty]

I recently started getting the following error message in Outlook 2003:

Task RP Computation – Sending reported error (0x800CCC78): “Unable to send
the message. Please verify the e-mail address in your account properties. The
Server responded: 501 mail not accepted from blacklisted IP addressâ€

The strange thing is that there are no messages in the outbox, but
nonetheless when I press Send/Receive, the progress bar at the bottom of
outlook shows “sending message 1 of 3†and after a few seconds the message in
the preceding paragraph pops-up

This only happens with one of my e-mail accounts, and it started happening
right after I did send tree messages from that account, but the messages did
left the Outbox, and in fact they are now in the Sent Items box.

I already tried the Scanpst.exe application, that did find errors in the
..PST file, which it reported as successfully fixed, but I still get the error
message.

This account is able to receive messages, but if I try to send any I get the
same error, and I have to manually delete the message from the Outbox.

If I access that account directly from the website of my service provider, I
have no problem sending and receiving e-mails, so it must definitely be
something that went wrong within Outlook when I sent those last tree messages.

I have tried deleting the account from Outlook and registering it again from
scratch, but there was no change.

 

[Andreas Roeder]

I recently started getting the following error message in Outlook 2003:

Task RP Computation - Sending reported error (0x800CCC78): "Unable to send
the message. Please verify the e-mail address in your account properties. The
Server responded: 501 mail not accepted from blacklisted IP address"

The strange thing is that there are no messages in the outbox, but
nonetheless when I press Send/Receive, the progress bar at the bottom of
outlook shows "sending message 1 of 3" and after a few seconds the message in
the preceding paragraph pops-up

This only happens with one of my e-mail accounts, and it started happening
right after I did send tree messages from that account, but the messages did
left the Outbox, and in fact they are now in the Sent Items box.

I already tried the Scanpst.exe application, that did find errors in the
.PST file, which it reported as successfully fixed, but I still get the error
message.

This account is able to receive messages, but if I try to send any I get the
same error, and I have to manually delete the message from the Outbox.

If I access that account directly from the website of my service provider, I
have no problem sending and receiving e-mails, so it must definitely be
something that went wrong within Outlook when I sent those last tree messages.

I have tried deleting the account from Outlook and registering it again from
scratch, but there was no change.

HI,
have you install a Virus program or a firewall?

 

[realmty]

No, There was no change in my system from the last time I used Outlook
without incident, to the appearance of the problem.

 

[Brian Tillman]

I recently started getting the following error message in Outlook
2003:

Task RP Computation – Sending reported error (0x800CCC78): “Unable to
send the message. Please verify the e-mail address in your account
properties. The Server responded: 501 mail not accepted from
blacklisted IP addressâ€

The strange thing is that there are no messages in the outbox, but
nonetheless when I press Send/Receive, the progress bar at the bottom
of outlook shows “sending message 1 of 3†and after a few seconds the
message in the preceding paragraph pops-up

Possible read receipts. See if this helps:
http://www.outlook-tips.net/howto/delete_rr.htm

 

[realmty]

Brian, that was it! I thought the problem was related to the last e-mails I
sent, but the issue was with the automatic read receipts, once I installed
OutlookSpy and followed the instructions in the link you provided, everything
is back to normal.