If you find a message wrongly classified as spam, you can unmark the message.
To do so:
- Select the "More" label, located on the right of your email. It should reveal the "Spam" label.
- Select the "Spam" label
- Select the message,
- Select the Not Spam button that appears at the top of your view.
- Unmarking a message as spam will automatically move it to your inbox.
- To find the message, select the "Inbox" label.
If you're still having issues, you can create a filter:
To prevent this problem from persisting for emails from a specific domain, follow the following steps:
1. Click the little triangle next to the search box at the top of the Gmail window.
2. Enter "@example.com" in the From box, then click "Create filter with this search"
3. Check "Never sent it to Spam" and any other filters you'd like
4. Click "Create Filter".