Mail Deliverability Checker
Full email authentication audit — checks SPF, DKIM, DMARC, BIMI, MTA-STS and TLS-RPT in one pass.
Frequently Asked Questions
What affects email deliverability?
Email deliverability is influenced by several factors: authentication records (SPF, DKIM, DMARC must be correctly configured), sender reputation (IP and domain reputation based on complaint rates, bounce rates, and spam trap hits), content quality (spam trigger words, excessive images, broken links), list hygiene (sending to invalid or unengaged addresses), and infrastructure setup (proper reverse DNS, matching HELO hostname, no blacklist listings). Fixing authentication issues is the most impactful first step.
What is email alignment in DMARC?
DMARC alignment requires that the domain in the message's From header matches the domain used for SPF or DKIM authentication. SPF alignment checks that the From domain matches the envelope sender (Return-Path) domain. DKIM alignment checks that the From domain matches the d= domain in the DKIM signature. Relaxed alignment (the default) allows subdomain matches; strict alignment requires exact matches. At least one mechanism must align for DMARC to pass.
Why is my email going to spam despite passing SPF and DKIM?
Passing SPF and DKIM only proves authentication — it does not guarantee inbox placement. Spam filters also consider sender reputation (has this IP or domain sent spam before?), engagement signals (do recipients open and interact with your emails?), content analysis (spam-like words, excessive HTML, misleading links), and list quality (are you sending to invalid or complaint-prone addresses?). Authentication is necessary but not sufficient for inbox placement — reputation and content quality matter equally.
What is a blacklist and how does it affect email?
Email blacklists (also called blocklists or RBLs — Real-time Blackhole Lists) are databases of IP addresses and domains known to send spam. Receiving mail servers query these lists to decide whether to accept email from a sender. Being listed on a major blacklist (Spamhaus, Barracuda, SURBL) can cause widespread delivery failures. Common causes of blacklisting include spam complaints, sending to spam traps, sudden volume spikes, and compromised mail servers. Use a deliverability checker to identify active blacklist listings.