Hello @ItaV44 ,
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 some general best practices for delivery. I'd also recommend setting your account up for self-authentication since 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:
Safelisting domains in a security system
Safelisting email addresses in an email client or security system
If you're wanting more in-depth, specialized insight on your current deliverability, it'd be worth speaking with one of our Delivery agents.
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