Sending, receiving, and organizing email in Outlook.com
Okay I got in touch with support today about this and did a screenshare. My error message was saying I was using 5.1GB of only 5GB available storage, which was strange because I should have 100GB email storage with my microsoft 365 subscription.
To resolve the issue i had to delete enough email attachments to go slightly below the 5GB allowance, this then allowed the new quota to take effect and my error message dissapeared on my desktop app and iphone app. very strange issue and lucky i had to delete very few attachments, I don't evny anyone who is using far more email storage than me.
This worked for me, thank you so much!