Hi @ogonzalesdiaz,
I have seen this earlier as well. Adobe is right with this suggestion to try and confine SMS deliveries to be sent from a single container only.
To add an affinity for SMS, you need to update the instance config file of the container from which you wish to send your SMS deliveries by adding an affinity name to the IPAffinity tag of your mta process
<mta autoStart="true">
<child>
<smtp>
<IPAffinity name="sms">
</IPAffinity>
</smtp>
</child>
</mta>
I have removed other elements/values to mask information, but you need to simply add the above attribute with value as "sms" (you can name it anything).
Second, you need to create a new typology for SMS deliveries, and in that typology add this affinity name in the affinity section.
You should be all set after you restart all services.
If you are hosted by Adobe, then raise a support ticket with them asking to add the affinity to the container's instance config file.
Regards,
Ishan