I once helped a friend by writing a simple script to automate sending series of mails which were usually composed manually with attachments and same-ish subject

I once helped a friend by writing a simple script to automate sending series of mails which were usually composed manually with attachments and same-ish subject and content. This boosted their productivity at least by 60%. I was more proud and satisfied with that simple piece of code than my entire professional work that year.