Deliverability
Deliverability guides and product notes — no filler.
SpamRats blacklist: why reverse DNS gets you listed
Why the SpamRats blacklist lists IPs for missing reverse DNS, how to check your PTR record, and how to fix and delist for free.
Invaluement blacklist: why your clean IP still gets blocked
Invaluement is a low-false-positive DNSBL that lists spam domains found in message bodies — so a link in your content can block mail from a clean IP.
The CBL blacklist and why a listing means you're compromised
The CBL flags IPs sending botnet and malware traffic. Learn why clean business IPs get listed, how it feeds Spamhaus XBL, and how to self-delist.
Email feedback loops (FBLs) explained
Email feedback loops forward spam complaints back so you can suppress complainers. How they work, which providers offer them, and why Gmail is different.
Dedicated vs shared IP for email sending
Dedicated vs shared IP for email: how each affects reputation and warmup, the volume that justifies a dedicated IP, and which one you should choose.
Email blocklists (DNSBLs) explained
Email blocklists (DNSBLs) can send your mail to spam for millions of recipients at once. How they work, how you get listed, and how to check and delist.
What is BIMI, and how to get your logo in the inbox
BIMI displays your verified brand logo next to authenticated mail in Gmail, Apple Mail, and Yahoo. Learn the DMARC, logo, and VMC requirements.
MTA-STS and TLS-RPT: encrypting mail in transit
How MTA-STS and TLS-RPT enforce encrypted mail delivery: what each record does, the DNS and policy-file setup, and a safe testing-to-enforce rollout.
How to read DMARC reports before you enforce
DMARC aggregate (rua) reports arrive as dense XML. Learn what they contain, how to spot legitimate sources failing alignment, and when to enforce.
How to warm up a new email domain or IP
How to warm up a new email domain or IP: build reputation gradually so your first big send doesn't land in spam — the ramp and the pitfalls.
How an email sending subdomain protects your reputation
A dedicated email sending subdomain keeps a bad campaign from torching your transactional mail. Reputation isolation, SPF/DKIM/DMARC, and warm-up.
Email list re-engagement: win back the dormant, protect the inbox
Re-engage dormant subscribers before they hurt deliverability: run a win-back campaign, set a sunset policy, and verify the list first.