Deliverability | DMARC Engine

18 June 2026 · 11 min read

The Google and Yahoo sender rules, one year on

A year after Google and Yahoo made authentication mandatory for bulk senders, here is what changed, how mail failed, and where enforcement is heading.

23 July 2026 · 39 min read

Optimising DMARC for Domains with High Volume Third-Party Senders

Optimise DMARC for domains with multiple third-party senders, avoiding false positives and phishing attacks

15 July 2026 · 38 min read

DMARC and Email Migration: A Step-by-Step Guide to Preserving Deliverability

Email migration can impact deliverability, DMARC helps prevent spoofing by verifying email authenticity

24 June 2026 · 12 min read

The complete guide to BIMI and VMC

A definitive guide to BIMI and VMC: the enforced-DMARC prerequisite, SVG Tiny PS logo rules, VMC vs CMC, which inboxes show logos, costs, and a full deployment checklist.

24 June 2026 · 14 min read

The complete guide to email deliverability

A definitive guide to email deliverability: authentication as the foundation, sender reputation, the Gmail/Yahoo/Microsoft bulk-sender rules, list hygiene, warmup and where DMARC fits.

5 June 2026 · 11 min read

Bounce handling and the return-path

The envelope return-path is where bounces come back to and the domain SPF authenticates. Here is how a custom return-path on your own subdomain fixes SPF alignment under DMARC, and what really happens to a bounce.

3 June 2026 · 11 min read

What DMARC reports do and do not tell you

Passing DMARC is permission to be judged on your merits, not a guaranteed seat in the inbox. Here is how to read aggregate reports for exactly what they measure, identity and authentication, without mistaking a perfect pass rate for good deliverability or panicking at failures that do not matter.

2 June 2026 · 12 min read

Dedicated vs shared sending IPs

Dedicated and shared sending IPs carry very different reputation trade-offs, and the right choice hinges on sustained volume, not folklore. Here is who should use which, and how the decision changes SPF, DKIM and DMARC alignment, plus what your aggregate reports reveal.

24 May 2026 · 11 min read

One-click unsubscribe: the List-Unsubscribe requirement

Google, Yahoo and Microsoft now require working one-click unsubscribe on bulk mail. Here is what the List-Unsubscribe and List-Unsubscribe-Post headers are, how RFC 8058 one-click actually works on the wire, how to implement it correctly, and why it sits alongside SPF, DKIM and DMARC on the same deliverability checklist.

24 May 2026 · 12 min read

Double opt-in and why it matters

Confirmed (double) opt-in keeps spam-trap hits, bounces and complaints off your list, the exact reputation signals that decide whether your authenticated mail reaches the inbox and clears the Gmail and Yahoo bulk-sender rules.

20 May 2026 · 11 min read

Why Gmail, Yahoo and Microsoft now require DMARC

Gmail, Yahoo and Microsoft now require SPF, DKIM and DMARC from bulk senders. Here is what each demands, what "require" really means, and how to comply.

20 May 2026 · 12 min read

How sender reputation works

Mailbox providers decide where your mail lands based on sender reputation, a private estimate built from how recipients react to your messages and how cleanly you send. This guide explains domain and IP reputation, the signals that raise and lower them, how to warm up a new sender, and why aligned SPF, DKIM and DMARC are what keep the reputation you build genuinely yours.

19 May 2026 · 12 min read

The 2024 and 2025 bulk-sender requirements in full

Google, Yahoo and Microsoft turned email authentication into a hard delivery gate. Here are the exact requirements, the numeric thresholds, who counts as a bulk sender, and a line-by-line compliance checklist.

18 May 2026 · 16 min read

Keeping your spam complaint rate under 0.3%

The spam complaint rate is the small, unforgiving number mailbox providers trust most. Learn how it is measured per provider, what pushes it past the 0.3% danger line, and the concrete steps that bring it back down.

6 May 2026 · 14 min read

Why legitimate email lands in spam

Real, useful email ends up in the junk folder when its signals look untrustworthy to mailbox providers. This guide breaks misfiled mail into its four root causes (authentication, reputation, content and complaints) and shows how to diagnose and fix each with concrete tools and steps, starting with the highest-leverage fix: authentication.

21 April 2026 · 13 min read

Feedback loops and complaint handling

A feedback loop (FBL) is how a mailbox provider tells you a user marked your mail as spam. Learn what FBLs are, how Yahoo, Microsoft and Gmail differ, how to enrol against your DKIM signing domain, how to read ARF reports, and how to keep your complaint rate under the 0.3% threshold.

7 April 2026 · 12 min read

Using Google Postmaster Tools

Google Postmaster Tools shows you how Gmail scores your domain and IP reputation, what share of your mail authenticates, your TLS coverage, and how often Gmail users mark your messages as spam. Here is how to read each dashboard, the spam-rate and reputation thresholds that actually matter, and how to pair it with DMARC aggregate data to find and fix the source of any problem.

3 April 2026 · 11 min read

Inbox placement testing

Inbox placement testing tells you where your mail lands (inbox, spam, a tab, or nowhere), which DMARC reports cannot. Here is how seed lists and panel tools actually work, where they mislead you, and how to cross-read their output with DMARC aggregate data so authentication faults and reputation faults stop looking identical.

2 April 2026 · 12 min read

IP warming for new sending IPs

A new sending IP starts with zero reputation, so a sudden volume spike reads as spam. Here is a sensible warm-up schedule, when a dedicated IP is even worth it, and how aligned SPF, DKIM and DMARC make the reputation you build stick to your domain instead of a leased IP.

1 April 2026 · 12 min read

List hygiene and deliverability

Authentication proves who you are; list hygiene proves you are wanted. Once DMARC enforcement welds reputation to your verified domain, dead addresses, bounces and spam-trap hits stop being diffuse problems and start hitting your signed identity directly. Here is how clean lists protect the reputation your SPF, DKIM and DMARC setup earns.

31 March 2026 · 12 min read

Using Microsoft SNDS and JMRP

Microsoft gives self-hosted senders two free feedback channels into Outlook.com filtering: SNDS for IP reputation, complaint bands and spam-trap hits, and JMRP for the individual junk complaints behind them. Here is how to enrol, read the data honestly, instrument your mail so complaints are traceable, and connect it all to your DMARC alignment so an Outlook deliverability dip becomes diagnosable instead of a mystery.

19 March 2026 · 12 min read

A subdomain strategy for sending mail

Splitting transactional, marketing and corporate mail across dedicated subdomains isolates reputation and shrinks the DMARC enforcement problem into small, independently controllable streams. Here is how to design the split, the exact SPF, DKIM and DMARC records to publish, and how to migrate without an email outage.