Hello @user573466 ,
Here are some general best practices for deliverability. If this is an email to internal contacts (i.e. those who share a work domain with you), then the lack of our standard live-send authentication associated with the test emails, combined with a lack of self-authentication from you may be causing the issue. Without at least some level of authentication, email security programs may treat a 3rd party service sending emails, posing as coming from your email address, as highly suspicious.
Deliverability 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. It's also a generally good idea to set up additional authentication for your emails - particularly self-authentication since you have you own domain.
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 Deliverability agents.
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