Pick a depth. Each prompt opens in your AI pre-loaded with the lesson. Click a row to preview the prompt.
SPF tells receiving mail servers which IP addresses are authorized to send email on behalf of your domain, blocking spoofing at the envelope level. Without it, any server on the internet can impersonate your domain and damage your reputation.
dig TXT yourdomain.com in a terminal and locate the line starting with v=spf1 — check whether your ESP's IP range or include directive is present.include: for a second ESP in a staging subdomain's SPF record and verify the lookup count stays under 10.