If your account sends email for more than one brand, location, or sending domain, there is a setting called Domain Configuration that controls which domain is actually used to send each type of email: campaigns, workflow emails, calendar reminders, payment notices, one-to-one replies, and client portal messages. This guide explains what the setting does, what happens if it is left unassigned, and how to set it up correctly.
This applies to any account with two or more dedicated sending domains set up under Settings → Email Services → Sending Domain. If your account only sends from a single domain, Domain Configuration is not relevant. The platform automatically routes all outbound email to your one domain, and there is nothing to assign.
Domain Configuration exists in Settings → Email Services → Domain Configuration. It lets you assign a specific sending domain to each category of outbound email:
Calendar Domain
Payments
One-to-One Conversation Domain
Bulk Email Domain
Campaign Domain
Workflow Domain
Client Portal Domain
Campaign Domain is the only field that can be split across multiple domains, with a defined percentage send split between them. Every other field on this page applies to your entire account and accepts only one domain at a time.
If any of these fields is left on "Please Select," the system does not leave that category of email unsent. It automatically falls back to a single default sending domain for that category, across your whole account. There is no warning, error, or failed verification when this happens, so an unassigned field can go unnoticed indefinitely.
This becomes a problem the moment your account sends for more than one brand or domain. Email authentication (SPF, DKIM, and DMARC) checks whether the domain shown in your "From" address matches the domain that actually signed and sent the message. This is called domain alignment. If Domain Configuration silently defaults a message to the wrong domain, the "From" address and the authenticating domain no longer match, even though your individual domains may each be fully verified on their own.
Example: An account has two verified sending domains, Domain A and Domain B. Workflow Domain is left unassigned, so the account defaults all workflow email to Domain A. A patient of Domain B receives an appointment reminder that says "From: Domain B," but the message was actually authenticated using Domain A's DNS records. Because the From domain and the signing domain do not match, inbox providers like Gmail and Outlook treat the message the same way they would treat a spoofed or impersonated email, and may block or reject it.
Enough blocked or rejected messages can cause your account's email sending to be automatically suspended, independent of your bounce rate or contact list quality. This is not a list hygiene issue. It is caused entirely by which domain a message is actually sent through versus which domain the recipient sees.
Step 1: Go to Domain Configuration. Navigate to Settings → Email Services → Domain Configuration.
Step 2: Review every field on the page. Check Calendar Domain, Payments, One-to-One Conversation Domain, Bulk Email Domain, Campaign Domain, Workflow Domain, and Client Portal Domain. Any field showing "Please Select" is currently relying on the account's silent default and should be assigned.
Step 3: Assign a domain to each field. For every field except Campaign Domain, choose the one domain that should handle that category of email for your entire account. You cannot split these by brand. Decide which of your verified domains should own each transactional email type, and assign it explicitly rather than leaving it on the default.
Step 4: Configure Campaign Domain's split. Campaign Domain is the only field that supports multiple domains. Assign each of your verified sending domains here and set the percentage split you want between them.
Step 5: Confirm Sender Domain at send time. When sending or scheduling a campaign, always select the specific Sender Domain that matches the brand you are sending as. Do not leave it set to "All Domains," since that rotates the send across every domain on the account and can reproduce the same authentication mismatch this guide describes.
Step 6: Re-check this page any time you add a domain. Domain Configuration does not re-prompt you when a new sending domain is added to the account. Any time you add another domain, return to this page and confirm every field is still correctly assigned.
This setting cannot fully separate multiple brands within one account. Calendar, Payments, One-to-One Conversation, Bulk Email, and Workflow Domain are account-wide settings. Whichever domain you assign to each will be used for that email category across every brand in the account, with no way to route it per brand. Only Campaign Domain supports a per-brand split.
Each domain being individually verified does not mean Domain Configuration is set up correctly. A domain can show fully verified SPF, DKIM, and DMARC records on its own and still send authenticated mail under the wrong "From" address if Domain Configuration routes that email category to a different domain by default.
This is a distinct issue from bounce rate or list quality. A domain alignment failure is an authentication and reputation signal, not a sign of invalid contact addresses. Reviewing or cleaning your contact list will not resolve this if the underlying cause is an unassigned Domain Configuration field.
If full brand separation is a priority, running each brand on its own account removes this risk entirely, since each account would have only one sending domain and nothing to assign or misconfigure. This is a structural decision best discussed with your Onboarding Manager or Customer Success Manager rather than a same-day configuration change.
Does this apply if I only have one sending domain? No. Domain Configuration only affects accounts with two or more sending domains. With a single domain, all email routes to it automatically.
Will I get an error if I leave a field unassigned? No. The platform does not display a warning or error. It silently defaults to a single domain for that category, which is why unassigned fields can go unnoticed until a message is blocked.
Can I split Workflow, Calendar, Payments, One-to-One, or Client Portal email by brand the same way I can with Campaign Domain? No. Those fields apply to the entire account and accept only one domain each. Campaign Domain is currently the only field that supports a per-brand split.
My domains all show "Verified." Why would I still have this issue? Domain verification confirms your SPF, DKIM, and DMARC records are correctly published in DNS for that domain. It does not confirm which domain the platform is actually using to send each type of email. That is controlled separately by Domain Configuration.
Is this related to my bounce rate? No. This is an authentication and domain alignment issue, not a list quality issue. Bounce rate reflects invalid or non-existent addresses; this issue reflects a mismatch between the From address and the signing domain.
What should I do if I am unsure which domain to assign to each field? Reach out to your Onboarding Manager or Customer Success Manager to review your account's domain setup together before making changes.
