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Email error when someone tries to email me - 451 Greylisted, please try again in 45 seconds

Error when someone tries to email me.

      Subject:             RE: 15 x X 50 mm  x various qtys / colours
      Sent:                 27/09/2007 07:13

The following recipient(s) could not be reached:
451 Greylisted, please try again in 45 seconds

The sender wants to know what to do.
1 Solution
Greetings worded !

Check if your ISP or server is blocking or greylisting the sender's domain.

Hope this helps, war1
Your e-mail system, or gateway, uses a DNS blacklist such as spamcop, sorbs, spamhaus, or CBL.
The e-mail system or gaeway that does this should also have the ability to add exceptions.  e.g. Exchange 2003 - go to Exchange System Manager, Global settings, right-click properties on Message Delivery, click on Connection Filtering tab, then click on the Eception button - you then add the sender's e-mail address here,

Best of luck!
You shouldn't see those messages.
Greylisting is a temporary failure and should not generate an NDR that can be seen by the user. The fact that you are seeing the message means something isn't working correctly.

When did the user get that NDR? On the day the message was sent or afterwards?

No idea what the posting above is on about. Greylisting has nothing to do with message filtering or blacklists on the server.

Get the user that got the bounce back to forward you the 'greylisted' notification e-mail along with its headers - this will help narrow down where the message was 'greylisted'.
I am also recieving this message only when I forward a message internally from a message that I recieved externally. It has to do with filtering, but it has more to do with the originating account which in my case is not handled by my local exchange server. So, a workaround is to change the account before I forward an e-mail that I recieved externally to my exchange server, which will then forward the e-mail internally without issue. Next to the "send" button, in my case there is an account dropdown in Outlook that offers me the option to use Exchange to forward the e-mail and I then do not get the 451 error.

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