Set up sending from a Wordpress sites domainmail

Good afternoon!
It is necessary to help with the refinement of the script for sending letters with attachments. Emails should be sent from the domain mail of the site, which is already created. The data comes from the front they need to be formed into a letter, attach all attachments, if their size is too large, you need to send a second letter in which it is indicated which files are too large and have not been sent. The mailing goes to the internal mail of the service and to the clients mail, if he specified one.
You also need a ticket counter, for example, set a value in MySql and use this counter in the subject/body of the email. A plus will be if the logic of the script is described in the comments.
Stack: PHP, MySql, Wordpress
Deadline: until 30.12.22
If we work together, such part-time jobs will be periodic,
In the application, specify the contact information