The first step is to configure your email that will send emails to users, in service center, example:

Remember to activate the IMAP / SMTP configuration on your email server, in my case I used gmail.com:

for gmail i had to activate this setting for less secure apps:

now let's go to the code!
Create an email as shown below:


Check security http:

then, in the action of your "PAY" button, make the update to pay the bill, and then drag and drop the email we created earlier:

the FROM field must be the email configured in your email account at the service center;
and the TO field, you assign the destination email to which you want to send the email (hotmail, gmal, etc.):

I did this procedure and the email arrived correctly:

was there any doubt?
see the attached example .OML.
Regards.