The first thing is to analyze the headers in order to identify why the emails goes to junk folder,
you may analyze in this link :https://mha.azurewebsites.net/ or download the app https://appsource.microsoft.com/en-US/product/office/WA104005406
After that, there are some actions to do like how to Create safe sender lists in EOP and allow entries in the Tenant Allow/Block List or you may train the spam filter. Mark false positives and spam as “not junk”. Doing this will help the spam filter recognize genuine emails in the future.
For your reference, you may go on to the https://security.microsoft.com -- email & collaboration, policies & rules, thread policy, antispam policy, Anti-spam inbound policy (Default) and review it.
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