Emails being moved to junk folder on Microsoft Office LTSC for no reason

I have Microsoft Office LTSC installed on 3 pcs, the E-mail account I have the issue with is on 2 different PCS, suddenly for no apparent reason some e-mails are being moved to the junk folder or deleted items, there are no rules set on this account and junk E-mail options are set to low: Move the most obvious junk mail to the junk Email folder.
Any suggestion as to why this is happening and how to prevent it?
Thanks Rebel24

Assuming that you have already added the domains for these emails to the Safe Senders List.
Add recipients to the Safe Senders List in Outlook - Microsoft Support

My guess on new emails that go straight to Junk would be that they were marked as SPAM by one of the email relay servers. Look in the Message Headers for a "X-Spamcause" entry.
View internet message headers in Outlook - Microsoft Support

For those that go straight to Deleted Items, I don't know of any standard Outlook operation that could do that except a Rule or some IT dictated Retention/Archive policy.

Right click on the Email and mark as "not spam/junk".
That will train the auto filter better in time.

Also you can put the sender on a safe senders list.
On my Email client that is Settings > Email > Junk Email > Senders > Add safe sender.

Same principles if you use the Webmail Access.

Thanks for the replies, just fail to understand why some of the emails suddenly started doing this (most of them are from addresses that we have received ail from with no problem)