Need a feedback after web phishing attack, restored the site, unblacklist and submission the URL for review/reclassify

Question

Hi there

We are helping this business where website gets a phishing attack 2 weeks ago. Their web developer fixed this by restoring it, patching it, tightening the security and removing possibly the backdoor entry via upload/contact forms. Last week, we found blacklisted from MXtoolbox and removed the blacklist on SURBL.org directly. The site is NOT blacklisted anymore for almost 7 days and we checked daily. However, we are still found in some cases where the recipient has sophisticated web/content filtering and the email might get blocked - small but not all.

We have been doing "submission the URL for analysis/reclassify" on firewall vendors, endpoint security vendors, etc by submitting to their websites and some coming back reclassify and some waiting. As Microsoft is their Defender, does anyone know how to do this on Microsoft 365 site? Is there URL for this?

Does anyone have an experience like this? Looks like every vendor keeps their own web content filter database. Do we need to contact them one by one? How to deal with this situation where we've done the web clean-up and unblacklisted and tried to submit the URL analysis/reclassify? Will it be like the respective system has TTL and look up again the blacklist and then the link will be ok?

I am appreciated your feedback.

Thanks