Inboxing emails

I built a desktop app MVP in electron with a node backend. I have people create an account in the app and my node backend sends them an e-mail to verify the e-mail adres. Most of my potential early adopters are within the organisation I work. Not to spend too much i registered a .xyz domain on namecheap. I am using this to send the e-mails but after a few e-mails the organisation my clients work for starts blocking my emails. Anyone have experience with this? I set up a DMARC record but this doesn't seem to improve my success.