
Note that we didn't really do email marketing aside from internal emails so I didn't have reporting to worry about skewing. I did this for birthday/anniversaries, and a workflow of about 30 emails, one a day, for onboarding, and a weekly internal newsletter. This would also open up more possibilities for accurate email performance reporting. Lastly, this is related to a popular request of mine in the HubSpot Ideas section.

If you're unsure, I'd recommend aligning with HR / legal. In others, there is legislation which specifies what is allowed and what isn't. In this case, you would be tracking employees. The bigger challenge, in my opinion, is that marketing emails are automatically tracking recipient behavior.

For reporting you should be good as long as you have separate campaigns for internal marketing emails and don't mix recipients lists. If anything, I'd assume that internal engagement with emails is higher and would, if at all, benefit email health. Unless you have employees which you expect to unsubscribe at high rates or even mark emails as spam, email health should not be a concern. Hi terms of reporting and email health, I don't see too many issues.
