Tools
Each one answers a single question by measuring your domain live. Free, no sign-up, nothing stored.
Check an SPF record
Reads the live SPF record for a domain, checks the enforcement policy, and counts the DNS-querying mechanisms against the limit that silently disables SPF entirely.
Check whether your domain can be spoofed
Anyone can put your domain in the From: field. What stops the message being delivered is a DMARC policy telling receivers to reject it. This checks whether yours does.
Check why your email lands in spam
Most spam-folder problems that come from configuration — as opposed to content or sending reputation — are visible in DNS. This checks the authentication records that receivers use to decide, and tells you which are missing.