Errorstoragelimit

I am trying to send an email with three image attachments which I have done several times before with Mailspring, however, I am now running into an issue where I am receiving this error message “Sorry, Mailspring was unable to deliver this message: Errorstoragelimit”

After receiving this error message, I went ahead and deleted over 700 emails, but am still unable to send. I don’t understand.

Edit: I am able to send emails without attachments. Only emails with attachments will not send.