Sending email reliably from PHP

"The email went to spam" is one of the most common support questions. The fix is usually outside the application.

• Send through SMTP from a real mail provider, not PHP's mail() function.
• Use a from address on your own domain.
• Add an SPF record listing your mail provider, and enable DKIM signing.
• Add a DMARC record once SPF and DKIM pass.

Then send a test from the admin panel and check the message headers: you want "pass" for SPF and DKIM.