I'm testing the Mandrill API and sent an email to my GMail account. In the API logs, it says:
"status": "queued"
According to https://mandrill.zendesk.com/hc/en-us/articles/205582717-Why-does-a-delivered-message-say-queued- :
most times Mandrill can send email much faster than recipient servers are able to accept or process it
GMail is not able to handle my one email that I sent?
A queued response in the Mandrill API is not the same as a queued response from a recipient server.
When you send a message through Mandrill, you first relay it to Mandrill, Mandrill processes it, and then Mandrill relays it to the recipient server. This all happens quite quickly, but the two relaying steps are separate and distinct. The KB article you've linked to is providing additional details on that last step, relaying to recipient servers, not a queued status for the Mandrill API.
There are a number of reasons the Mandrill API may respond with queued including if you've added attachments or if you're sending to a bunch of recipients in a single API call.
Without seeing the actual API call that's being made, it's hard to say why you're getting a queued response. But if you're using the sample messages/send API call, you'll want to remove all of the optional parameters that you're not actually setting. For example, the sample has fake attachments, and a subaccount specified. The attachment will cause the call to be processed async. The subaccount probably doesn't exist, and would then cause the call to fail. So if that's the case, try removing all of those optional params. If not, please provide the API call you're making with sensitive data redacted (API key, actual email addresses).
The reason might be either hourly/monthly quota is over or you are using same multiple accounts for single public ip server.
来源：https://stackoverflow.com/questions/32172638/mandrill-status-queued