Using Outlook for iOS for personal email and calendar management
Same here, hundreds of spam messages per day not being blocked.
My Outlook address has become practically unusable due to this.
The only way round this is to stop using Outlook. I've had the same problem all year. I forward the spam on to Microsoft and our government's National Cyber Security service here in the UK and block each email individually. Doesn't work. On checking the email domain name (which belongs to Microsoft) with the NCS service it states the DMARC policy (anti-spoofing) is set to "none" and MTA-STS (Mail Transfer Agent Strict Transport Security) is not configured. Shocking. I only discovered this today - a major failure by Microsoft.