Hello there mguerra,
We see you're looking for help with blocking senders as you're getting a lot of junk messages, so let's see if the following information can help out.
For starters, let's be sure you're up to date with the latest supported macOS version. If an update is available, be sure you have a recent backup of information prior to installing the update. If you need assistance with this, check out the following steps found here: Update macOS on Mac
Before you get started, it's a good idea to back up your Mac. Then follow these steps to find and install any available software updates or upgrades.
1. From the Apple menu in the corner of your screen, choose System Preferences.
2. In the System Preferences window, click Software Update.
If your System Preferences doesn't include Software Update, learn how to upgrade to macOS Monterey or upgrade to an older macOS, and use the Updates tab of the App Store app to get app updates.
3. Click Update Now or Upgrade Now:
* Update Now installs the latest updates for the currently installed version, such as an update from macOS Big Sur 11.5 to macOS Big Sur 11.6.
* Upgrade Now installs a major new version with a new name, such as macOS Monterey. Software Update shows only upgrades that are compatible with your Mac.
Once you confirm that you're up to date with the latest macOS version, let's check out the following steps which speaks to blocking senders. Additional information can be found here: Block senders in Mail on Mac
Block senders
1. In the Mail app on your Mac, select a message from the sender you want to block.
2. Move the pointer next to their name in the message header, click the arrow, then choose Block Contact.
The Blocked icon appears next to the sender’s name in the message list and a banner is added to their messages to indicate they’re blocked. The banner also provides a link to the Blocked pane in Mail preferences where you can manage blocked senders.
You can also add senders directly to the list of blocked senders. Choose Mail > Preferences, click Junk Mail, then click Blocked.
If that isn't helpful, restart your Mac to see if that will clear up what you're experiencing. If not, let us know which macOS version is currently installed. Also let us know if you're able to add senders to the blocked list.
Have a great day!
