I cannot send emails from my iPhone, getting "No Space Left on Device" error message.
A short time after I attempt to send an email using the iOS Mail app, I will see an error message appear stating "Cannot Send Mail", then a message about not being able to connect to the SMTP server for outgoing mail and then ending with "No Space Left on Device" or something to that effect (Don't have a screenshot to share unfortunately). What exactly causes this message to display? How can I remedy this so it doesn't happen again in the future?
I have ~40gb of storage on my iPhone and 180gb on iCloud (I do NOT use iCloud email so it isn't an issue related to that)
EDIT: Attached screenshot of error message
iPhone 11