Sending Notifcation for Issues via API Request

Hello!

i wanted to send notification for Specific Issues through an API request.

https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-issues/#api-rest-api-3-issue-issueidorkey-notify-post

In the documentation is mentioned , if the Request was succesfull the mail is qued up for sending.

And i got some Succesful requests, but the mail has not been send.

Hence, is my Question how long can a Mail be in que? Or can i trigger the que?

Best Regards

Fabian