Configuring SAP domain which is also used by another marketing platform

I’m working with a client to setup the SAP for their domain where the SAP domain is ‘’ (well, similar anyway).

They are currently using a different marketing platform and will be migrating over to Marketing Cloud over a re-platforming phase.

In the meantime, they need to send from both platforms (their current marketing platform and Marketing Cloud).

I’m aware that there are multiple DNS entries used by the Sender Authentication Package (SAP), but from this list, the only two that are currently used by the existing platform are:

  • (two MX records with a priority value of 10)
  • (TXT record for

I know that the MX record is only required for outbound email (SFMC uses a separate MX record to route replies). So, I should be able to add the additional MX records for Marketing Cloud (I assume the priority doesn’t matter either, as it won’t be used to route inbound mail).

Also, while there is an existing SPF record for, which looks like this:

v=spf1 -all

I know that you can add additional include: keywords to existing records, e.g. this can be modified to:

v=spf1 -all

Does anyone know if there is an issue with setting the same subdomain as SAP in Marketing Cloud, while also using it concurrently with a different marketing platform?

This would be quite a common scenario for customers migrating to Marketing Cloud and wanting to retain their existing subdomain. I believe that in theory, this should be possible.


From a reputation and operational point of view, it does make sense to keep the domains separate.

E-Mail reputation is not only based on IP, for some providers, notably gmail, domain reputation is more important, and apparently gaining importance (source for this is a Salesforce deliverability slide).
So: especially during (IP) Warming, where you try and have a very controlled setup, if you run into reputation issues whose root cause you have to identify and mitigate, it will be hard to trace where the reputation problem originated.

In other words: the strategy of establishing a “clean” reputation during Warming by using your “new” setup (IP + domain) for sending only to your best performing subscribers first will not be possible. The
ongoing, “old” mail provider’s sendouts would be on the same domain and confound your efforts.

Of course it is also safer for the “new” sendout system to be isolated from the old, so no legacy debt is inherited.

So: While it seems technically possible, since the configuration is more complex but the risk is higher and standard practice for warming becomes impossible, this is generally discouraged and (in my experience) mostly avoided.

Source : Link , Question Author : Eliot Harper , Answer Author : Jonas Lamberty

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