Subdomain Set-up

Updated 7 months ago by Chris Hundley

Using a custom subdomain allows Siftrock to directly capture and process the replies to your marketing email. There are 3 steps you will need to complete, each outlined in more detail below:

  1. Create a DNS record for your subdomain, pointing an MX record to Siftrock.
  2. Set-up DKIM signing and a SPF record for your subdomain.
  3. Update the FROM and REPLY TO fields in your MAP to use your subdomain.


1.) DNS Settings: Point your reply subdomain to Siftrock

Name the subdomain whatever you want. e.g. or

Edit the DNS for your subdomain so it points to our server. Note: Our server will only handle replies -- this does not impact your sending at all.

We have a primary and secondary service for redundancy. You should add both of these MX records to your DNS configuration:      MX     10
       MX     20

This will direct emails to any address to the Siftrock mail server.


2.) Configure DKIM signing and a SPF record for your subdomain

Note: This is not a required step for Siftrock to function, but it is a recommended best practice for deliverability.

Generally you will create a SPF record on your new subdomain that matches the SPF record on the domains you currently use for email marketing. In addition, you will want to configure DKIM signing in your MAP platform for your new subdomain. This requires adding the domain in your MAP admin for email domain management and passing the required DNS information to IT.


3.) Edit the FROM and REPLY TO fields to use the sub-domain on your next send.

You will need both the FROM and REPLY-TO fields in your campaigns using an alias at your Siftrock subdomain.
Our system wildcards the alias, so you can set the FROM and REPLY TO with any alias... i.e. webinars@, jennifer@, marketing@, etc.


Background: How it Works

Siftrock manages an inbound SMTP server that handles email responses on behalf of our customers. When someone in your organization sends an email they wish to have managed through our service the reply-to and from email address at a specific sub-domain is used to direct responses to the Siftrock SMTP server.

Best-practice for email marketers is to use a friendly sub-domain such as or To make this work seamlessly we require an MX record to be configured in your DNS pointing at our mail server, and we highly recommend you also configure an A record as well.

Our mail server for handling customer replies is

Depending on your DNS provider it can take anywhere from a few minutes to a full day for the new sub-domain record to be available for use.

Once your DNS and software setup are complete your marketing team will be able to start using the new reply-to domain in all their outbound campaigns.

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