DKIM
7 articles
DKIM alignment and forwarding
A valid DKIM signature is not the same as DKIM alignment. This guide explains how alignment is evaluated, why DKIM is the one signal that survives forwarding while SPF cannot, and exactly how relays and mailing lists affect it.
Read more
1024-bit vs 2048-bit DKIM keys
2048-bit DKIM is now the baseline every major mailbox provider expects, but a 2048-bit public key will not fit in a single DNS TXT string. This guide covers the real security trade-offs, the 255-byte per-string DNS limit and how chunking works, the exact way each major DNS provider wants the value entered, and how to verify the published key actually parses before you rely on it.
Read more
How to rotate DKIM keys safely
DKIM signing keys decay in security the longer they live. This guide shows how to rotate them using selectors, with full overlap and verification, so legitimate mail never drops a signature or fails DMARC during the change.
Read more
DKIM selectors explained
A DKIM selector is the label that points a receiver at the right public key. Here is what selectors are, how to read them out of a message and DNS, and how multiple selectors let you rotate keys without an outage and let many senders sign one domain.
Read more
How to enable DKIM in Google Workspace
A step-by-step guide to enabling DKIM for a Google Workspace domain: generating a 2048-bit key in the Admin console, publishing the public key as a DNS TXT record (including the 255-byte chunking that trips people up), verifying it is live, and turning on signing safely in the right order.
Read more
How to enable DKIM in Microsoft 365
Microsoft 365 signs your mail with a shared Microsoft domain by default, which does nothing for DMARC alignment. This guide walks through enabling DKIM signing for your own custom domain end to end: finding the exact CNAME values, publishing the two selector records, switching signing on, and verifying the result really passes.
Read more
What is DKIM and how does it work?
DKIM attaches a cryptographic signature to every message you send, letting receivers verify with a public key in DNS that the mail really came from your domain and was not altered. Learn how signing and verification work step by step, how to read the headers and DNS record, and why a DKIM signature survives forwarding that breaks SPF outright.
Read more