{
"message": "External communications may not be replaced",
"code": "postino.error.transfer.replace.external",
"status": 400,
"messageWithParams": "External communications may not be replaced",
"messageParams": {},
"contextId": "ce9ee5e8-9af6-4a8f-86c3-a151bf17bb41",
"details": [],
"errors": []
}
Based on the error your receive:
What participantId are you using in your API request?
This error makes me think that you are trying to use the participantId of the customer [participant with "purpose" equal to "customer" or "external"].
You have to use the participantId of the queue (where your email is currently queued) [participant with "purpose" equal to "acd"].
If this is already what you are doing, I would suggest to open a ticket with Genesys Care, so they can investigate and check if something is stuck with this conversation.
The participant has to be active/connected.
If this is indeed the last participant in your conversation (I mean that the participantId you are using is the one of an active acd participant), then I would suggest to open a ticket with Genesys Care.
We don't have access to customer data/environments on this forum. So I don't know how your conversation context looks like.
And if something is stuck in your conversation, Genesys Care should be able to help/explain.
"We would like to Review these old emails and Transfer to agent. But Assign option has condition Agent Needs to be on queue and accept the email and on top of that, Agent should have same queue assigned. Please help me here."
I don't understand what you mean by "removed from Assignment Services". Do you mean that it no longer shows up in the Queues Activity details view for a queue? If so, then it cannot be assigned using that feature since a queue musty be involved.
If you are still experiencing problems with that same email, you should contact Product Support (formerly Care) as Jerome suggests.