Check the headers. It may not even originate from Strava. Many spammers spoof the identities of legit companies, stealing logos, etc.
There are all kinds of ways for spammers and phishers to target audiences. Any tracking from browsers and apps can provide enough data to target a likely user of Strava or other online business. Doesn't mean the email originated from Strava.
Same method used by most junk callers now. Doesn't do any good to block the numbers because they're spoofed. Blocking phone numbers may block a legit caller who actually owns that number.