all have the suffix "@outlook.com". so, instead of blocking those 3 email addresses individually, you are able to block the @Outlook.com part, as a collective. Of course, this then results in legitimate emails being sent to your spam folder, so it then becomes necessary to set an alternative filter rule. If you get spammed by ads for viagra, bitcoin, etc from email addresses, you can set up the filter rules to pre-scan your emails, looking for VIAGRA, or BITCOIN or whatever, to then divert those emails to your spam folder. Initially, it is time-consuming, but after a while, you should reap the benefits of using filters. Use Google to search for best advice on how to use filters in your email client. I think if you set this up using a computer, the filters are done on the client servers, before you will retrieve your emails on your phone.
Hmm. Roughly how many Spam email accounts have you added. Just roughly. The only thing I could think it could be would to do with your Gmail, Google Photos and Google Drive 15gb limit. Even if you don't use the latter two I believe it counts towards your 15gb limit. But saying that, adding an email address to your spam would hardly take up much space, if any. Do you happen to know what storage you have left on your Google account? My Gmail takes up 0.25gb but I barely use it and don't send many attachments.
Check to see if you can create filters, as I suggested, above. That 500 can probably be whittled down quite a bit if you are able to assign filter rules. So, instead of, say 50 email addresses trying to entice you to invest in bitcoin, by applying "bitcoin" as the filter word, you have gone from blocking 50 individual email addresses, to just ONE filter block. Likewise, if "viagra" is another filter word. Just by applying filter rules to those 2 words alone, you have reduced that 500 to just 402!!