Email Deliverability & DMARC Glossary for E-commerce Senders
A "human-readable" guide to the technical acronyms that determine whether your Shopify revenue lands in the Inbox or the Spam folder.
DMARC
Critical Priority
What it is
Domain-based Message Authentication, Reporting, and Conformance. It is the rule that tells Gmail and Yahoo exactly what to do if an email claims to be from you but fails the ID check (SPF/DKIM).
Shopify Context
Without a DMARC record, you are non-compliant with 2025 Bulk Sender rules. However, setting DMARC to "reject" without fixing your Shopify alignment first will cause your order confirmations to bounce.
SPF
Foundation
What it is
Sender Policy Framework. Think of it as the "Guest List" for your domain. It is a text record in your DNS that lists every IP address and service (like Google, Shopify, Klaviyo) allowed to send email on your behalf.
Shopify Context
Merchants often break SPF by having "Too Many Lookups." The limit is 10. If you add Shopify, Klaviyo, Gorgias, Zendesk, and generic marketing tools, you will hit this limit and your emails will start failing.
DKIM
Authentication
What it is
DomainKeys Identified Mail. A digital "wax seal" on every email. It proves that the email hasn't been tampered with during transit and that it truly originated from the owner of the domain.
Shopify Context
This is the most common failure point. If you do not add the CNAME records Shopify provides to your DNS host, Shopify cannot sign the email. This forces them to rewrite your sender address to
[email protected].
Error 5.7.515
Outlook / Microsoft
What it is
A specific rejection error code used by Microsoft (Outlook, Hotmail, Live.com). It means "Authentication Failure." The email was not just filtered to junk; it was blocked completely.
Shopify Context
This happens frequently to Shopify brands that have not set up a "Dedicated Sending Domain" in Klaviyo. Microsoft is stricter than Gmail and will block high-volume senders who rely on shared pools.
Alignment
Concept
What it is
When the "From" address users see matches the domain authenticated in the technical headers (SPF/DKIM).
Shopify Context
Alignment is the "Gold Standard." Generic setups are usually "Un-aligned" (e.g., Mail comes from
sendgrid.net but says it's from brand.com). DMARC requires alignment to pass fully.
BIMI
Brand Visibility
What it is
Brand Indicators for Message Identification. A standard that allows your brand's logo to appear next to your message in the customer's inbox (Gmail, Apple Mail).
Shopify Context
This is the "blue checkmark" of email. You can only get BIMI if you are at strict DMARC enforcement (p=reject or p=quarantine). It dramatically increases open rates and trust.
Dedicated Sending Domain
Klaviyo Setup
What it is
A subdomain (like
send.brand.com) that you configure in Klaviyo to send emails, instead of using Klaviyo's shared domain (klaviyomail.com).
Shopify Context
Essential for removing "via klaviyomail.com" from your header. Without this, you are sharing your reputation with thousands of other merchants, which risks your deliverability.
CNAME Record
DNS
What it is
Canonical Name Record. A type of DNS record that maps one domain name to another. In email, it's used to point your domain keys to your provider.
Shopify Context
Shopify and Klaviyo both require CNAME records to enable DKIM signing. If your IT person says they "added the TXT records" but ignored the CNAMEs, your authentication is incomplete.
p=none
DMARC Policy
What it is
The "Monitoring Only" mode of DMARC. It tells Google/Yahoo: "Tell me who is failing authentication in a report, but deliver the mail anyway."
Shopify Context
This is the safe starting point. We always start clients at p=none to gather data before moving to strict enforcement, ensuring we don't accidentally block legitimate order emails.
p=reject
DMARC Policy
What it is
The "Strict Enforcement" mode. It tells Google/Yahoo: "If an email fails authentication, delete it immediately. Do not deliver it."
Shopify Context
The ultimate goal for brand protection. Once you are here, nobody can spoof your domain. But if you rush here without fixing Shopify alignment, you will break your business.
Spam Rate
Metric
What it is
The percentage of recipients who mark your email as spam. This is calculated daily by mailbox providers like Google.
Shopify Context
The hard limit is 0.3%. If you exceed this, Google will start blocking your domain regardless of your authentication status. We monitor this via Postmaster Tools.
Postmaster Tools
Google Utility
What it is
A free dashboard provided by Google that shows your domain reputation, spam rate, and authentication errors for emails sent to Gmail users.
Shopify Context
This is your "Credit Score" for email. We set this up for every client to prove that their spam rate is healthy and authentication is passing.
List-Unsubscribe Header
Requirement
What it is
A hidden code in the email header (RFC 8058) that enables the "Unsubscribe" button at the very top of the inbox, next to the sender name.
Shopify Context
Mandatory for bulk senders in 2025. If you don't have this, Gmail and Yahoo may penalize you. Klaviyo inserts this automatically, but only if your domain is properly authenticated.
Hard vs. Soft Bounce
Metric
What it is
A Hard Bounce is a permanent error (email doesn't exist). A Soft Bounce is temporary (mailbox full, server down).
Shopify Context
High hard bounce rates destroy your reputation quickly. If you see soft bounces specifically at Outlook/Hotmail, it is often actually a "Block" (5.7.515) disguised as a bounce due to bad auth.
RUA / RUF
DMARC Reporting
What it is
Tags in your DMARC record. RUA sends aggregate reports (safe, summary data). RUF sends forensic reports (individual failure details).
Shopify Context
We enable RUA to monitor your health. We strictly disable RUF to ensure we never receive your customers' private data or PII in failure reports.
MX Record
DNS
What it is
Mail Exchange Record. This tells the internet where to deliver *inbound* email sent to your domain.
Shopify Context
Often confused with SPF. MX records handle incoming mail (like customer support replies), while SPF handles outgoing mail (like Shopify order confirmations). You need both.
DNS Propagation
Concept
What it is
The time it takes for changes to your DNS records to spread across the internet's servers. Can take anywhere from minutes to 48 hours.
Shopify Context
When we fix your SPF or DKIM, you might not see the green checkmark in Shopify immediately. This delay is normal. We verify changes directly to ensure they are live.
Suppressions
Klaviyo Term
What it is
A list of email addresses that have unsubscribed, bounced, or marked you as spam. Klaviyo automatically stops sending to them.
Shopify Context
Never delete your suppression list to "clean up." If you email those people again, your spam rate will spike, and you will get blocked by Gmail immediately.
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