Delivery Status Notification (Failure)
550 5.7.26 Unauthenticated email from medi.com.co is not accepted due to domain's DMARC policy. Please contact the administrator of medi.com.co domain if this was a legitimate mail. Please visit https://support.google.com/mail/answer/2451690 to learn about the DMARC initiative. k8sor1812313ybh.196 - gsmtp
Following these steps helped me to solve this problem
How Senders Deploy DMARC in 5-Easy Steps DMARC has been designed based on real-world experience by some of the world’s largest email senders and receivers deploying SPF and DKIM. The specification takes into account the fact that it is nearly impossible for an organization to flip a switch to production. There are a number of built-in methods for “throttling” the DMARC processing so that all parties can ease into full deployment over time.
1. Deploy DKIM & SPF. You have to cover the basics, first.
Activate DKIM following this https://support.google.com/a/answer/180504
Activate SPF following this https://support.google.com/a/answer/33786?hl=en&ref_topic=9061731 Ensure that your mailers are correctly aligning the appropriate identifiers.
2. Publish a DMARC record
Follow this https://support.google.com/a/answer/2466563?hl=es
3. Test that everything is working with this
https://dmarcian.com/dmarc-inspector/ https://toolbox.googleapps.com/apps/checkmx/check?domain=medi.com.co&dkim_selector=