Outlook - all mail marked as SPAM

I work at the Office of the RV park i live in during the summer months... I had gotten an email the other day from our Manager and he was saying that all email coming in, usually winds up in his "junk" or "spam" folder.

When i check the mail in the Office, I open Outlook, and all the mail is marked SPAM - it is literally added to the Topic line, so when you reply or forward the SPAM is right there.

When i used to do "Bulk" mailings thru Thunderbird, i would never have this issue.

Is this an Outlook thing? possibly in our settings? The Mgr also commented that on his Iphone, or whatever phone he uses to get his email - it does the same thing... it's a Gmail address.

anyone have any idea what i'm referring to?

the MGR was saying something about looking into a Bulk Mail software program - saying that would be a coupla hundred bucks.... but this SPAM thing is not just from Bulk Mail being sent, it's even individual emails. so i'm thinking it may be more in our settings from our host??

any input would be great.

Terese