How to fix issue of not sending email whereas system notes it sent?

QUESTION: 

I use the module v1.2.2 for my site Magento 2.3.4. It worked fine before but stop sending email last night.

For testing, change the config Frequency cron to */5 * * * *  (sending an email every 5 minutes).

Screenshot: https://i.imgur.com/5mxYGYe.png

However, the system notes that email was sent but there is no email coming - https://i.imgur.com/dYvo6dI.png..

Do you know how to fix this?

QUESTION: 

To resolve this issue, please edit file app/code/Bss/ProductStockAlert/Model/Email.php as below:  

Or download the attached file below and overwrite the current file on your site.

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