Hello @AmyD19027 ,
The only other influencing aspect that could be contributing to it from this side would be your account's current authentication setup. Since you're sending using your own domain for the From address, it's best to use self-authentication.
Beyond that, it'd just be a matter of that recipient checking their email program's settings, making sure you're safelisted in their program, or reaching out to their email program's support.
See also:
Email Authentication FAQ
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