Subscribe to a Google Group with your non-gmail email

You can subscribe to any Google Group with your non-gmail email. If you try to subscribe through the web interface, you’re typically forced to use a gmail account. The solution is quite simple, but few people know about it.

For a Google Groups group, send an email to groupname+subscribe@googlegroups.com.

For a Google Apps group, send an email to groupname+subscribe@domain, for example, chromium-dev+subscribe@chromium.org.

You’ll receive a reply if you’ve successfully subscribed. Note: when I did this, my first email to a +subscribe@ address was delayed by ~10 minutes.

Reference: How do I subscribe to a group?