I can sympathise,
I'm now doing Microsofts work trying to find ways end users can stop the tsunami of spam that Outlook allows through,
I'm not sure what format you use Outlook in, a version of a client installed on your PC, via a mobile, or you visit your Outlook account online via outlook.live.com,
for clarity what I propose refers to a mailbox located on outlook.live.com,
but can apply equally to any other email client installed on your PC or mobile, though the wording and options might vary,
spammers know you visit your mailbox and view their email spam before deleting it because when you view it outlook delivers the images in the email from the spammers server and that tips them off,
in outlook.live.com, settings>email>junk email>filters, tick the box: "Block attachments, pictures and links from anyone not in my Safe senders and domains list"
as a consequence any email in your mailbox, inbox or junk mail, should be headed with the warning: "Some content in this message has been blocked because the sender in't in your Safe senders list"
because the pixel tracker isn't being loaded you're viewing the message without tipping off the sender,
if it's a trusted sender you can click on "I trust content from abc@xyz" and they'll be added to your 'Safe senders and domains' list.
if it's phishing spam you can add the sender address to your 'Blocked senders and domains' list,
I hover over the senders address, a panel drops down including the senders address, if you hover over the end of the senders address in the drop down an option to copy the address appears,
copy it there,
open settings>email>junk email, at the top of the 'Blocked senders and domains' list is: +Add, click on that to open the box, paste in the copied address, hit the enter/return key on your keyboard and it should add to the list and a 'Save' dialogue box should open at the bottom,
click that to save the entry,
that email address will never make it into your mailbox again,
if you want to block a specific domain and all email from it then edit the entry from: ******@potato.clam to potato.clam
this will block everything from potato.clam,
obviously you can't block domains like outlook.com, gmail.com, yahoo.com, but you can block troublesome websites that send spam with modified sender names,
return to the malicious email and click on the 'report as phishing' button, this will delete the email,
when you've finished your cleanup, go to deleted items, empty folder, then select "Recover items deleted from this folder" which opens a folder containing everything you've deleted and empty that folder,
I'm in the UK, my very first step is to forward every phishing email to The National Cyber Security Centre so that they can examine it and take appropriate action, their reporting address to forward suspicious email to is on the page linked below;
https://www.gov.uk/report-suspicious-emails-websites-phishing
for the last week I've Blocked attachments, pictures and links from anyone not in my Safe senders and domains list,
forwarded every suspicious email to the NCSC,
added the sender to my Blocked senders and domains list,
added repeat offending domains as domains to the list,
reported the email to Microsoft as phishing via their reporting button,
deleted the email,
deleted the email from deleted items,
deleted the email from recover deleted items,
what was a couple of dozen emails a day has reduced to one or two, which I still treat in the same way.