@alexr I bet in a lot of cases you could just munge the address a bit while keeping it recognizable for your tracking. Like if you're registering for "Service", create "s3rvice@mydomain.com" or "fartservice@mydomain.com" 
toddz@social.linux.pizza
@toddz@social.linux.pizza
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Dear services that refuse email addresses that have the name of the service in the address: