Terms below appear throughout guides on email design and accessibility. Each definition is one or two sentences; follow the links in the sidebar for the full guides.
Core terms#
Email design and accessibility
Accessible email design ensures messages render and can be read across clients and by people using screen readers or high contrast: semantic HTML, alt text, sufficient contrast, readable font sizes, and a logical reading order.
SPF
A DNS record listing servers authorized to send for a domain. Checked against the connecting IP.
DKIM
A cryptographic signature on each message, verified with a public key in DNS.
DMARC
A policy record telling receivers what to do when SPF and DKIM fail alignment, plus reporting.
Alignment
Agreement between the visible From domain and the domain that passed SPF or DKIM.
Sender reputation
A provider's running assessment of a domain or IP based on complaints, bounces, engagement, and authentication.
Inbox placement
Share of accepted mail that lands in the inbox rather than spam.
Spam trap
An address that never opted in, used to catch senders with poor list practices.
BIMI
A DNS record pointing to a brand logo displayed next to authenticated mail; requires DMARC enforcement.
Feedback loop
A provider program that reports recipient spam complaints back to the sender.
Frequently asked questions#
Does dark mode change email colors?
Some clients invert or adjust colors. Test in Gmail, Outlook, and Apple Mail dark modes and use transparent PNGs where possible.