1. Use anti-spam plugins:
There are several excellent plugins that can filter and block spam messages:

A. Akismet Anti-Spam
Description: The most popular and free anti-spam plugin.
How to use:
Install the plugin from your dashboard.
Get an API key from Akismet.
Activate it and it will start filtering spam comments automatically.
B. CleanTalk Anti-Spam
Description: A paid but very effective plugin that offers protection for email, comments, and contact forms.
Pros:
No Captcha required.
Automatically filter spam comments.
C. Antispam Bee
Description: A free plugin with no ads. Ideal for personal websites.
Pros:
Supports filtering comments based on user language.
No registration or API key required.
2. Use CAPTCHA or reCAPTCHA:
Adding CAPTCHA to forms (such as a comment or contact form) significantly reduces spam messages.

How to do it:
Use a plugin like Google reCAPTCHA or WPForms to enable CAPTCHA tests.
Integrate Google reCAPTCHA with WordPress:
Get a reCAPTCHA key from Google.
Add the keys to the appropriate plugin.
3. Set up a Firewall:
Use a firewall that helps block spam or malware.

Recommended plugins:
Wordfence Security: Comprehensive site protection with the ability to block suspicious IP addresses.
Sucuri Security: A paid but very effective plugin.
4. Optimize WordPress settings:
Close old comments:

Go to: Settings > Discussion > Close comments on posts older than [X] days.
This reduces spam in old posts.
Pre-approve comments:

Enable the option Comments must be manually approved on the same page.
5. Block spam IP addresses:
If you are receiving spam from known sources:

Identify suspicious IP addresses through the Logs.
Add it to your block list via plugins like Wordfence.
6. Change or reduce the visibility of your admin email:
Make sure your admin email is not visible on your site to avoid being targeted.
If you use a contact form, replace direct mail with sending messages via the form.
7. Check your hosting:
Some hosting companies offer server-level spam protection. Contact your hosting provider to see what options are available.
Suggested plan:
Start using Akismet or CleanTalk to filter spam.
Add Google reCAPTCHA to forms.
Use a firewall like Wordfence.
Review your comment settings and restrict them if necessary.