part of your problem might be with the .co , since outside of tech industry circles or people who are actually Colombian, it's rare and weird. I bet you'd halve the problem or more if it was a .net or similar.

.co is actually fine usually as people in Australia are familiar with .co.uk and .co.nz (even though the “co” means different things in those contexts)

I share a name with a US Governor which is great for keeping my teenage internet activity buried in search results but made it tricky to find a suitable domain name.

I own osdev.(com|net|org) and I've experimented with using different email addresses over many years. The .net and .org TLDs still cause a lot of confusion. I'd guess that .edu is questioned the least after .com. But even .com addresses from non-common domains cause people to question them.

[email protected] - no problem. [email protected] - I'm sorry, can you repeat that for the forth time?

I've experimented with other domains using common English words and its no better.

I still like to use a personal domain to register with most sites but if I have to give someone an email address over the phone its going to be a common email hosting service that forwards to my real email.