Need to modify VBA code from excel format to userform for making it more dynamic

Hi All Expert,

I've attached an xlsm file that you can use to send bulk emails with multiple attachments and an HTML signature. "Email Sender" and "Email Designer" are two worksheets in the file. Now, I'm thinking of making it more dynamic, and instead of using an excel file, I'd like to use this coding and format as a userform, so that I can add it to Excel as an add-in and use it to send bulk mail as a feature. I'd appreciate it if you could assist me in making it more dynamic. I will be grateful to you. Thank you.