Gmail

Gmail-specific features, settings, and deliverability requirements.

7 articles

March 2026

CaptainDNS · March 23, 2026

Gmail Verified vs Google Verified: understanding the real differences

The Gmail blue checkmark and the Google verified badge rely on entirely different mechanisms. This guide breaks down the technical prerequisites, costs, and steps for each verification.

February 2026

Diagram of an email rejected by Gmail with 550 5.7.26 and UsernameCaseMapped errors

CaptainDNS · February 26, 2026

Gmail 550 5.7.26 and UsernameCaseMapped rejections: causes, diagnosis, and fixes

Gmail rejecting your emails with 550 5.7.26 or UsernameCaseMapped? Technical causes, step-by-step diagnosis, and SPF/DKIM/DMARC fixes to resolve these permanent bounces.

January 2026

Illustration: Gmail address change with alias and account retention

CaptainDNS · January 6, 2026

Change your Gmail address: an option rolling out at Google

Google documents a long-awaited feature: replace your @gmail.com while keeping your account, emails, and services. Here's how to prepare.

December 2025

CaptainDNS · December 16, 2025

BIMI, VMC, CMC: compatibility and DNS prerequisites (Gmail, Yahoo, Apple Mail)

Putting your logo in the inbox: what you actually need to configure in DNS for BIMI, and how to choose between VMC and CMC.

Diagram: Gmail "Unsubscribe" button triggering an RFC 8058 POST to an opt-out endpoint

CaptainDNS · December 15, 2025

Gmail/Yahoo one-click unsubscribe: what RFC 8058 changes and how to implement it

Gmail and Yahoo require a one-click unsubscribe via RFC 8058-compliant List-Unsubscribe headers. Here's the expected format, the server-side POST, and the compliance checklist.

Diagram showing Gmail stopping POP fetching from external accounts in 2026

CaptainDNS · December 5, 2025

Gmail ends POP fetching from other accounts in 2026: impact and action plan

Starting January 2026, Gmail will no longer continuously fetch messages from external mailboxes via POP ("Check mail from other accounts"). Impacts, timeline, and alternatives for Gmail and Google Workspace users and admins.

November 2025

New Gmail rules 2025: bulk senders beware

CaptainDNS · November 6, 2025

Gmail tightens its sending rules: what's changing for senders starting November 2025

Starting in November 2025, Google enforces new security requirements for bulk senders: full SPF/DKIM/DMARC authentication, TLS encryption and strict unsubscribe management.