WordPress contact form not sending email: what to check, in order

1 · Did WordPress even hand it over?

Look at what the visitor sees after pressing Send. An error means wp_mail() returned false and PHPMailer, the library inside it, gave a reason — typically “Could not instantiate mail function.” That sentence means PHP's mail() isn't working on this server. Most form plugins swallow that reason; your host's error log may have it.

2 · Is an SMTP plugin in the way?

If you use WP Mail SMTP, FluentSMTP or similar, its own log and test email come first. An expired password, a changed app password or a mailbox that now requires two-step sign-in breaks every form on the site at once.

3 · Is the From address on your domain?

A notification “from” the visitor's Gmail address, sent by your web server, fails the receiving server's checks. Use an address such as wordpress@yourdomain in From, and put the visitor's address in Reply-To so you can still answer them.

4 · Is it arriving, but as spam?

Search the spam folder and your mail provider's quarantine. If it's there, the headers of that message tell you exactly why — the receiving server records its SPF, DKIM and DMARC verdicts at the top. The guide to emails going to spam has a checker that reads them for you.

5 · Meanwhile, stop losing enquiries

A form that only emails is a form that can lose a customer silently. Mailbag Contact Form writes each entry to its own table before the email is attempted, so a broken mail setup never costs you the message. Each entry shows Sent to your mail server, Failed with the exact error, or Not sent; you can resend it once the mail works again, and a notice on Mailbag's screens counts the notifications that failed and says when the problem started.