Can I use a subdomain for email sending?

Yes, you can use a subdomain (e.g., mail.yourcompany.com) as your email domain. Setup is the same: add SPF, DKIM, and DMARC records for the subdomain in your DNS provider. Verify the subdomain in Resend, then use it as your 'From' address. Subdomains are a good way to separate email from your main domain.