Lost email moved from spam

I had an email in my hotmail spam folder. I moved it to the inbox and it disappeared! Possible causes of a problem 1. The email came from a private email domain eg info@companyname.com. It is a small company which uses outlook, a previous email also ended up in my spam even though it is genuine, (And I know from experience that kind of email address can cause problems in my setup) 2. Both emails had an attachment - the first one I moved using thunderbird desktop, not android, directly to the inbox of another email account with no problem. 3. All email to my hotmail automatically gets forwarded onto a gmail account (not leaving a copy in hotmail). However if I mark an email as not spam/move to inbox in thunderbird (desktop) it doesn't get forwarded on, stays in the hotmail inbox. I have just moved another message (telling me I'd signed in here) from my spam to inbox using thunderbird android and it has appeared in my hotmail inbox - so I suspect the attachment might be the issue? Any advice of how I can get it back? (and also what exactly caused the issue) I have searched both email accounts (including trash and spam and all mail) and it isn't appearing anywhere... searched/looked in thunderbird desktop and both email accounts online and it has gone ... Thanks