system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why we can send emails from gmail to yahoo or outlook but cannot do the same with instant messaging apps like WhatsApp to Messenger or iMessage?
gpt
Email was deliberately designed as an open format. It was created at a time when the ppl who controlled the internet cared more about making it work, than they cared about maintaining control over it.

Messenger apps were deliberately designed as closed formats, bc by the time it was a thing, the value that big companies saw in the internet was maintaining control over their user base, and selling that user base to advertisers.

TLDR: different end goals. Email was designed for you to use it, message apps were designed to use you.