SendPaw Mail

PHP 7.4 is the minimum. The plugin is compatible with PHP 8.0 through 8.5, including the stricter null-argument handling introduced in PHP 8.1: every value is cast to string before it reaches trim(), preg_replace() or similar, so a null coming from wp_mail() headers or an unset settings field never triggers a deprecation notice. The plugin declares all class properties explicitly, so it is unaffected by the deprecation of dynamic properties (PHP 8.2) and will keep working when that becomes an error in PHP 9. It uses no functions or extensions removed in PHP 8.5.

Yes. A subdomain such as mail.example.com or news.example.com is added and verified as a domain in its own right, with its own SPF, DKIM and (optionally) tracking and bounce records published under that subdomain. Note that verifying example.com does not automatically authorise its subdomains — add each sending subdomain separately, and make sure the From: address on this settings screen matches a verified one.

The API sends through SendPaw's HTTP endpoint (faster, and less likely to be blocked by hosting firewalls). SMTP sends using the standard SMTP protocol to SendPaw's ingress. The plugin can use the API as the primary method and automatically fall back to SMTP if the API fails.

SendPaw can be self-hosted, so every instance has its own hostname — there is no single hostname that works for every user.

Yes. Attachments passed to wp_mail() — WooCommerce invoices, form uploads, and so on — are sent over both transports. On the API path the server validates each file against an allowlist of types and the operator's size/count limits, and rejects the message if a file isn't allowed rather than delivering it without the attachment.