Simplify validation to check DNS records instead of MX records
Remove redundant port 80 checks that fail for mail-only subdomains
Maintain compatibility with services like Mailgun and SendGrid
This commit adds the PHPMailer Lite library to the vendor directory. The
library is a lightweight version of PHPMailer designed for sending
emails with support for SMTP, Sendmail, and IMAP transports. It includes
features like HTML email composition, attachments, and embedded images.
The library is licensed under the MIT license and requires PHP version
8.0.0 or greater.