Scheduler is running but not sending emails

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

https://community.zammad.org/t/asking-for-help-on-community/2262/2

### Infos:
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* Used Zammad version: 
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### Expected behavior:

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### Actual behavior:

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### Steps to reproduce the behavior:

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