Disapperaing mails

I looked at my emails and I had received a couple of cost prices mails from work  that I had asked work to send over and I also saw an enquiry from a company for a potential order. 

I look back again about an hour later and the enquiry was gone from my inbox, not in the deleted box nor junk either. 

I look again this morning and the cost prices emails that I had sent over from the office are gone. I have other emails from other people, even another email that came from a prospective client through the work inbox and I replied to it through hotmail, so the functions seem to be ok, it's just that a few mails have gone missing and all of them are business related and important.

I am suspicious because there is inconsistency here - the mail that I replied to remains but the others have gone. Is it possible for a hacker to remove certain mails like this, please? Is it possible that someone could remotely delete mails in an attempt to cover their tracks about something? Is it possible that there is industrial espionage taking place and these mails are being mined by another company? Only the potential order that hadn't been replied to and the mails about cost prices have disappeared.

Thank you,

Reece.