During the email validation, DMARC checks the following identifiers: 'from' address email domain, return-path address, DKIM-signature domain. If one of the domains used by DKIM or SPF matches with the domain in the 'from' header, the email passes the DMARC alignment check.
The following diagram shows the process sequence of DMARC alignment check:

Types of DMARC Alignment
There are two types of DMARC alignment:
JetSend supports both Strict alignment and Relaxed alignment.
How JetSend Supports DMARC Alignment?
As part of setting up a sending domain, you can set up a custom return path for your domain. One of the many tasks the DMARC system does is to check for alignment between sender name and return-path name. So, a custom Return-Path that aligns with your sending domain helps you achieve full DMARC alignment.
For a step-to-step guide on setting up a custom return path, see DMARC Alignment section in the Set Up Sending Domains in JetSend article.