Configuring Email for Use with Delfa: DNS Setup Guide

Last updated: July 30, 2026

To send and receive emails from your own domain within the Delfa platform, you need to set up a dedicated subdomain and add specific DNS records so that emails route correctly through Delfa's infrastructure.

Overview

Rather than using your primary domain directly, Delfa uses a subdomain (for example, trials.yourdomain.com) so that outbound emails are sent from addresses like info@trials.yourdomain.com and inbound replies are routed back into the platform.

This keeps recruitment emails separate from your main domain.
Because outreach volumes can be high and automated, the subdomain protects the sending reputation of your primary domain if messages are delayed or flagged as spam. That way, your coordinators’ normal day-to-day email deliverability is not affected.

Once the subdomain is agreed, you will need to add the following DNS records through whoever manages your domain's DNS settings (e.g., your IT team or DNS hosting provider).

Required DNS Records

DKIM and SPF Records (Outbound)

These records are required to authenticate outbound emails and improve deliverability.

Type	Host / Name	Value	Priority
TXT	`resend._domainkey.<subdomain>`	DKIM public key (provided by Delfa)	—
MX	`send.<subdomain>`	`feedback-smtp.us-east-1.amazonses.com`	10
TXT	`send.<subdomain>`	`v=spf1 include:amazonses.com ~all`	—

Receiving Record (Inbound)

This record is required to receive inbound email replies from participants back into the Delfa platform.

Type	Host / Name	Value	Priority
MX	`<subdomain>`	`inbound-smtp.us-east-1.amazonaws.com`	10

Replace <subdomain> with the subdomain label agreed with your Delfa onboarding team. For example, if your subdomain is trials.yourdomain.com, the subdomain label would be trials.

Important Notes

Both the outbound (DKIM/SPF) and inbound (MX receiving) records are required. Without the receiving record, replies from participants will not be routed back into the platform.
DNS changes can take some time to propagate. Once the records have been added, notify your Delfa onboarding team so they can verify the configuration.
The exact DKIM key value will be provided by the Delfa team as part of your onboarding — do not use a placeholder value.
This only gives Delfa permission to send emails from that subdomain, not your main domain

Need Help?

If you are unsure which subdomain to use, or need the specific DKIM key value for your account, please contact the Delfa support team and they will provide the details specific to your setup.