HomeBlogEmail Deliverability News: Latest Gmail, Yahoo & Outlook Updates
Stay up to date with email sender requirements, deliverability changes, and spam filtering updates. See what changed, who is affected, and what to check.
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Version 2.0 of the M3AAWG guide covers breach notices, recalls and court-ordered mail that has to reach people who opted out long ago.
Who is affected
ESPs and companies sending breach notices, recalls or court-ordered mail.
What to check
Version 4.0 replaces the 2011 and 2015 documents, with more on address collection, domain warming and being transparent about data.
Who is affected
Senders warming a new domain or subdomain, and the ESPs that host them.
What to check
From September 14, 2026 young tenants get a fraction of their external recipient quota, and trial tenants are held to 500 recipients a day.
Who is affected
New Microsoft 365 tenants, trial tenants and schools on free Education licenses.
What to check
The DMARCbis documents are out. The pct, rf and ri tags are gone, np, psd and t are new, and a DNS tree walk replaces the Public Suffix List.
Who is affected
Every domain with a DMARC record.
What to check
A DMARC working group draft asks to end the ARC experiment, stop relying on ARC between unrelated parties, and move RFC 8617 to Historic.
Who is affected
Anyone counting on ARC to carry mail through forwarders and mailing lists.
What to check
The April 2026 revision of M3AAWG's TLS for Mail recommendations rules out everything older than TLS 1.2 and asks mail operators to log TLS details.
Who is affected
People who run their own mail servers.
What to check
From April 15, 2026, Spamhaus blocklist queries sent from Oracle's network to the public mirrors return 127.255.255.254. The fix is a free DQS key.
Who is affected
Mail servers on Oracle's network that use the public Spamhaus mirrors, and anyone who mails them.
What to check
Google's v2 API exposes the full Postmaster Tools data, compliance status included. The v1 API and the reputation dashboards are on their way out.
Who is affected
Teams that pull Postmaster Tools data into their own dashboards or alerts.
What to check
Basic authentication for SMTP client submission in Exchange Online will be off by default for existing tenants at the end of December 2026.
Who is affected
Printers, scanners, scripts and apps that send through Exchange Online with a username and password.
What to check
The per-mailbox cap of 2,000 external recipients a day, due from April 2026, is cancelled. The 10,000 recipient limit stays in place.
Who is affected
Organizations that send to external recipients from Exchange Online mailboxes.
What to check
From November 2025 Gmail answers non-compliant mail with temporary and permanent rejections, where before it mostly filtered or deferred it.
Who is affected
Everyone sending to personal Gmail accounts. The stricter rules start at 5,000 messages a day.
What to check
Yahoo added Insights to Sender Hub, with delivered volume and spam complaint rate per verified DKIM domain, counted on inbox mail only.
Who is affected
Anyone sending to Yahoo Mail who signs with a DKIM domain of their own.
What to check
Each entry reaches the feed with its source, so the update lands where your team already reads.
A rule changes once.
Your mail runs into it
every day.
I add an entry when a mailbox provider, a blocklist or a standards body publishes something that changes what a sender has to do. Every entry links to the original announcement. The date is the day it was announced or, where the provider published no dated post, the month it took effect. Rumours and reposts don't get in, so if a change has no primary source you won't find it here.
Every sender needs SPF or DKIM, valid forward and reverse DNS, TLS, and a spam rate under 0.3% in Postmaster Tools. Above 5,000 messages a day to Gmail you also need both SPF and DKIM, a DMARC record, an aligned From domain, and one-click unsubscribe on marketing mail. Since November 2025 mail that breaks these rules can be rejected outright.
Close to them. Yahoo's bulk rules also ask for SPF, DKIM, DMARC, an aligned From domain, one-click unsubscribe and a spam rate below 0.3%. Like Gmail, Yahoo gives you two days to honor an unsubscribe.
Outlook.com has required SPF, DKIM and DMARC from high-volume senders since May 2025, and the Outlook guide covers those rules and the 550 5.7.515 bounce. The next date on the calendar is for Microsoft 365 tenants: password-based SMTP AUTH goes off by default at the end of December 2026.
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42 checks on SPF, DKIM, DMARC, blocklists, unsubscribe headers and content, plus the folder it lands in at Gmail, Outlook, Yahoo and other providers. Free, no signup.