From time to time I glance through my spam folder to gauge how the filters are working, and if they're catching any "ham." Most of the spam is really obvious, but I'm getting a few which made me wonder if somebody is using my email (presumably in systems which do not require double-opt-in).
Some of the mails simply make no sense as spam, but I guess they might be tests if my mailbox bounces the request or not.
Are there relatively pain-free ways to find out if that is the case? In a couple of weeks the new EU General Data Protection Regulation comes into force and I could just ask companies what they have on me, but that would be a lot of work for me and for them, and fruitless if the sender was forged.
Re the comment, I hestiated to do give examples because it might "smear" a perfectly legitimate service.
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Subject: Welcome to Heathrow Wi-Fi - let us help you explore