Scheduler is running but unable to send emails

Very new to Zammad:
In my application, I get all the mails, expect for the once that are scheduled by schedular.
I have a scheduler written, in which it has to send a mail and add a specific tag to ticket.
It adds the tag which means it runs but mails are not going

Closing - duplicate of:

Please don’t create dozens of threads about the same topic.
This wastes time of people trying to help you and steals it from other members that might not receive an answer because of that.