Sent Email not being received thru App

After a painful 2hours with Microsoft and getting three different people who all said they can't help I am finding it hard to believe I am the only person with this issue

When I send email the recipients are not receiving (sent test to myself)

I was having this issue with the outlook App and also web browser the second person was able to get web- browser to work, when I asked what happened, the answer was it is an Outlook glitch (omg)! Then I asked about App I got transferred again and was told to talk to outlook which was the second person. Ever since I purchased 365 have had nothing but issue with outlook.

Hoping someone can help me with my Outlook sending issues

Thank you in advance