Problem with junk mail

Many of incoming emails from trusted senders regularly end up in the Junk folder. Their contacts are in the Address Book.
On arrival, I move them to my Inbox, uncertain of the effect of removing either “email” or “domain”. Neither appears to make any difference; the problem continues.
Would re-installing the program (free version) solve rectify the situation, without losing previous content?
I would appreciate any comments and advice.

This really depends on what is moving the messages to Junk to begin with.

Normally, it is your server, so you will need to login to their webmail interface, select the message in spam, and mark it as not spam. Thereafter the server should always leave messages from that sender in the Inbox.

But it can also be caused by eM Client moving the messages if you have previously blacklisted the sender or their domain. If that is the case, go to the Junk folder and right-click on the message choosing Move to Inbox > Move to Inbox and remove blacklisted …
This option will have no effect if it is the server moving the messages.
You can also go to Menu > Rules and edit the Blacklist Rule if you have one. See if the sender’s address or domain is in the list and remove it.

The Spam filter Rule will move messages to Junk if the server has marked them as spam but not already moved them. You can either train the server not to mark them as spam, or disable this Rule if nothing else helps.