Programmatically set the "To" field

Hi Support.
So we are currently building a web builder that automatically installs Contact Form 7 plugin.
One of the requirements is be able to set the user’s email address as the the default “To” value.
I was able to locate that the info in the Contact Form’s “Mail” settings is stored in the wp_postmeta table.
A snippet of the data saved in wp_postmeta is as follows:

[your-message]”;s:9:”recipient”;s:{SOME NUMBER}:”{EMAIL ADDRESS HERE}”;s:18:”additional_headers”;s:22:”Reply-To: [your-email]”;s

I was able to successully set (via MySQL scripts) the value of {EMAIL ADDRESS HERE} above.
But the {SOME NUMBER} data seems to be set by a certain value.
I can’t figure out how it can be done or how should the number be generated.

Please help and thanks in advance.

https://ww.wp.xz.cn/plugins/contact-form-7/