No idea about Youtube accounts.
# Use Cloudflare Email Routing.
* Point your MX records at their MX. * Cloudflare forwards email to your gmail.com address.
* In Gmail Settings: "Add another email address". * Add your SMTP settings in the new account. * There is no need to configure IMAP or POP3.
# Use Cloudflare Email Routing.
# Use AWS SES or some other transactional mail provider.