Every Sunday at 9am I send out an email to ~1000 people. Most of our board has gmail accounts and we did not receive the email till around 2pm. I don't know if it's a gmail issue (I wasn't going to scan 1000 accounts to see when they opened our email.) Can you tell me why it took so long for us to get our CC email? Thanks.
It sounds like the receiving email programs or ISPs were gating the emails you were sending.
Delivery can have a lot of variables, from elements on our side, on your side, on the recipient's side, and in their email system company's side. Here are somegeneral best practices for delivery. I'd also recommend setting your account up forself-authenticationsince you have your own domain, which can greatly affect delivery timeliness, trustworthiness, and overall success.
If you'd like to learn more about safelisting, and what it entails: