Getting Too Much Spam Mail from IBM Dev and How to Stop It

Over the last few months, I have been receiving a huge amount of spam emails from IBM. One day, I checked my spam folder and found 42 emails from their site. I think there must be a glitch in their system that caused this sudden flood of emails.

I reached out to their support team about the spam. An IBM representative instructed me to email another department regarding the issue. After I explained the situation to them, they assured me they had deleted my account and that I wouldn't receive any more emails.

It stopped for a few days, but now I am getting these spam emails all over again. If anyone knows a better way to block these permanently in Gmail, please let me know.

Here is an example of the spam emails I'm receiving:

Despite being told that my account was removed and that the emails would stop, I am still getting a massive amount of spam every week, as shown in the screenshot.