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"Rejected by SLM Monitor" error message for Canada Post shipments.

New Contributor



Recently it has become almost impossible to process a shipment for Canada Post because we keep getting the error message "Rejected by SLM Monitor". Apparently, this is the error message that pops up when we have a lot of requests per given minute or if our account with Canada Post is restricted but neither is the case for us. We do probably one parcel every few minutes and after checking with Canada Post, there are absolutely no restrictions on our account. Are there any other users who are experiencing this and have found a solution?


We did contact Shipstation support but they were useless. First they insisted that our account had a limitation set on it by Canada Post or we were sending in too many requests per minute. When finally we were able to make them understand (after several emails back and forth) that neither was true, they finally claimed that Canada Post has put a limitation on the Shipstation API and that WE, who have no ownership in Shipstation or even know what an API is should contact Canada Post and discuss ways on solving the problem that the Shipstation system has with them. Abysmal support.


We'd appreciate it very much if anybody has found a solution for this. Thank you in advance!



We don't have a perfect solution either, but sharing our experience. 


We do periodic sales campaigns, where we can ship 1,000 units in a week via Canada post, and we get the same "Rejected by SLM Monitor" when doing an ENDOFDAY close.  We batch our closing so it doesn't stress out the Canada Post feed.   We just RETRY  until all units have been verified, and it can take up to 20 RETRY's.     


I read somewhere that Canada Post API  / server throttles the transaction flow when there is a lot of volume flowing through.    It is seriously frustrating.   I don't know if this a Shipstation integration issue or a Canada Post issue, but neither side will agree they are the problem.  



In our case it's not even 10 waybills a day when this happens... Quite frustrating as you said and we also keep hitting that retry button until the waybill finally prints.


Though we've noticed that in the past week or so, the issue has improved and we've not encountered the problem so far so hopefully someone took action on this.


Good luck!


same situation happened to us - and response from shipstation was the same. There was no cap on our commercial CP account, and no excessive requests were made. Next day the service was okay. It seems anytime the status page on canadapost website has some issues with the system listed, shipstation is fast to blame CP and suggests no solution. When we call up canada post about it, they cannot troubleshoot it because our account is connected through shipstation service. It happened a few times just recently that we coudn't print EOD papers, and the two parties have no resolution strategy. It would be great to feel that the two are working together to ensure a good service, instead of throwing the ball at each other and leaving the client helpless. @shipstation - what's your thoughts?