[redstripe]

This would certainly be convenient, however if your mailing lists contains a lot of old people then they forward your emails to their friends. Their friends who are annoyed by this then unsubscribe the original recipient without noticing that the email was forwarded by their friend.

This is a real problem for us - not a made up scenario. So we remove the auto-filled email on the unsubscribe form.

[tcgv]

A way to mitigate this issue is to ask for a confirmation before marking the email address as unsubscribed, showing the retrieved email address in a large font as to prevent someone who received a forwarded email from mistakenly unsubscribing someone else.