Edit: I am thinking of creating a folder "never to be seen" and having
all correspondance from said email to this folder.
You want to create a filter.
- find a message from this email address and select it.
- Click the "More" button and Select "filter messages like these"
- In the window that pops up, in the bottom right corner click "Create Filter with this search"
In the new window that pops up select:
- skip the inbox
- apply the label
- Never send to spam
when you select "apply the label" you must select an existing label or create one.
- Optional: you can click on the option to apply filter to X matching conversations.
- Click "Create filter"
Now the new label will be applied to that message and all new messages. They will not go to spam, they won't appear on the front page.
I am not sure it will catch emails already in spam. I didn't test it for that.