Emails sent but not delivered to recipient

For several weeks now I've been having trouble getting emails delivered from my Hotmail email address. It's intermittent so sometimes emails are received. Doesn't appear to matter what the recipients email address is. Happens with yahoo, gmail, shaw and outlook emails. Happens whether I use my phone or my laptop, whether I use webmail or the outlook app. Also happens connected to wifi, ethernet or cell phone data. Any ideas? It's showing in my sent folder so I have no way of knowing which emails are delivered unless I call the customer on the phone to ask them. The majority are not being delivered. Extremely frustrating. I was told by microsoft support to perform a reputation check 5-6 times in 24 hours but that hasn't seemed to help at all.