I've found that "My firstname dot my lastname at gmail" works great over the phone. I don't even have to say dot com everyone understands "gmail."

It's a good email address, custom domains for email addresses are somewhat rare and often end up being more confusing than helpful. Unless it is support at domain dot com or info at domain dot com.

Not for personal addresses facing the general public though, I wouldn't think. Even something as simple as "My firstname at domain dot com" you'll end up spelling out the domain one time out of two whether you've been talking about it - or not.