I prefer how the R mailing list works: No attachments of any kind and no HTML messages allowed. Just plain text email. If someone needs to supply something too large for a single email, they must put it on a Web site (such as GitHub, for example) and then include a URL for that. That is: (1) much safer for all; (2) saves bandwidth for uninterested users; (3) save space on the various archives. Yes, this is very "retro" of me. And only a personal opinion, not a commandment from on high.