SigPro allows us to create signature files that refer all images in the signature to images located on a web server instead of sending the images as attachments. We use a program called SigPro for MacOS 10.13.x and below and MailSuite for MacOS 10.14.x which includes a newer version of SigPro. Our company recently switched from Rackspace IMAP mail to Microsoft 365 Exchange mail.
I apologize in advance for the wordiness of this question:
