Email Deliverability Tools
When mail stops arriving, the cause is nearly always authentication, routing, or reputation. Work these tools in order: confirm mail is routed (MX), then that receivers can verify you (SPF, DKIM, DMARC), then that nothing is blocking the sending IP (PTR, blocklists, port reachability).
Diagnostic order
All email deliverability tools
Mail servers and priorities for a domain
Validate SPF syntax and count the 10-lookup limit live
Build a correct SPF record with provider presets
Find and validate DKIM keys — selector discovery included
Policy, alignment, and why Gmail may reject you
Create a DMARC record with a safe rollout policy
Is your IP or domain on a DNS blocklist?
Can your mail server be reached on ports 25/465/587?
Decode Received chains, SPF/DKIM/DMARC results, and delays
Is SMTP TLS policy published and valid?
Brand logo record status for your domain
SPF + DKIM + DMARC + MX + PTR on one screen
Guides for email deliverability tools
The current single-MX setup, verified, with per-registrar steps.
How mail servers choose between MX records, and common priority mistakes.
The diagnostic order that finds what a nameserver change broke.
Why SPF breaks at 10 lookups and how to flatten your record safely.
Exactly what to publish, what not to add, and how to verify it.
What each qualifier does at real mailbox providers in the DMARC era.