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Re:Show HN: OnAir – create link, receive calls by pqdbr on Friday November 15, 2024 @08:32AM (#42146758)
Congrats on launching!

Curious how the dynamic image works in the e-mail signature: AFAIK, Gmail and others heavily cache any images inside e-mail, so even if the image changes, Gmail will be displaying the online/offline cached image, not the most up-to-date one.

Re:Show HN: OnAir – create link, receive calls by bigmicro on Friday November 15, 2024 @08:38AM (#42146807)
You can overcome this using headers, which instructs Gmail not to cache. Snippet:

response.headers["Cache-Control"] = "no-cache, no-store, max-age=0, must-revalidate"

response.headers["Pragma"] = "no-cache"

response.headers["Expires"] = "Fri, 01 Jan 1990 00:00:00 GMT"

Re:Show HN: OnAir – create link, receive calls by floobertoober on Friday November 15, 2024 @10:13AM (#42147611)
You might want to investigate this further - IIRC a lot of email services retrieve images in advance server side to avoid leaking whether the client has interacted with the email. I might be mistaken here.