hundreds of emails from ceos and companies

I woke up to find my mailbox clogged with hundreds of emails from companies and or their ceos that my email address had been compromised. I got 100 of these from one company alone. The emails all contained links to the companies, and when I moused over the links they looked legitimate. But I did not click on the links because hey if you get 100 emails from the same companies and your mailbox is full of such from many places, something is phishy. What do you think is going on? Is there a way I can/should block these senders? Thanks if you have advice.

Can you please post an example of it, preferably the source code of it?

In Thunderbird you can press CTRL-U to see all details.

Could it be related to this issue discussed here?