Hi all, I have created subdomains example mkt.myapp.com, sales.myapp.com, and reports.myapp.com Now for each subdomain & main domain if I connect a different mail server then will email deliverability get impacted for an entire domain? Let's say reports.myapp.com will send thousands of emails daily if by any chance it gets blacklisted then will it impact other subdomains and the main domain?

YES. Validate all email address before you start sending emails. Provide an unsubscribe feature. Configure and setup SPF, DKIM and DMARC. Ref: 1. https://simonandrews.ca/articles/how-to-set-up-spf-dkim-dmarc 2. https://support.google.com/a/answer/10032473?hl=en&ref_topic=2759254

You said YES does that mean if one subdomain is impacted it will impact other subdomains and main domain as well?

You said YES does that mean if one subdomain is impacted it will impact other subdomains and main domain as well?

Yes, domain and subdomain gets impacted. Its hard to get email deliverability once you lose your sending reputation.

But domain and subdomain both are considered as different domains by most of the companies right?

The answer is in your comment - by most of the companies. It depends on the company's email policy. Also, you can check the exact values of SPF, DKIM and DMARC for some reputed firms like GMail, ICICI Bank etc. for further understanding.

Can I make use of email warm up tools in that case?