Hello @Josephinum1890 ,
My recommendation would be to check with those affected contacts, to see if safelisting your account's sending email in their personal settings will aid in the deliverability. Otherwise, you could also speak with your organization's IT team to make sure our domains are safelisted. It'd also be a good idea to set up self-authentication.
If you continue to have issues, then I'd recommend speaking with our Deliverability team for more specialized insight and troubleshooting.
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