Gmail has an automated system that helps detect spam by identifying viruses and suspicious messages, finding patterns across messages, and learning from what Gmail users like you commonly mark as spam.
If you are receiving spam:
Things to note in this message:
1. There is no address in the "To:" field; 2. IT always signs our messages with "ITD" and would include the HCC helpdesk email and phone number; 3. ITD would never ask you for any information by email; 3. It is highly unlikely that you will ever run out of storage space for your email :)
Things to note in these messages:
1. IRS will never ask for your personal information by email; 2. It says its from IRS.gov but the email address is a HCC email; 3. The subject line in image 2 has a misspelled word