In my experience they're not, these are way less popular in enterprises as compared to Microsoft equivalents.
Sure it's less popular. It came in under 20 years ago, competing against an entrenched superpower that was already nearly 30 years old back then. It's done pretty well.
The Google Apps for Business bundle has outsold by far ever single FOSS email/groupware stack in existence, and every other commercial rival as well.
Notes is all but dead. Groupwise is dead. OpenXChange is as good as dead. HP killed OpenMail.