make event filtering case insensitive
If we then query the event API for incoming mails for "email@example.com" we will not see the mail for "FOO-BAR@domain.com". It seems that the event filtering _is case sensitive_. So we need a query for each possible capitalization in order to see all possible incoming messages.
(We tried using regular expressions with a flag to make it case insensitive, but it seems that regular expressions are not allowed with event filters.)
It would be helpful (and less surprising) if event filtering on e-mail addresses would match the same addresses as the routing does. I.e. make it case-sensitive.
Some background info on why we need this: as the Mailbox API is being removed we thought of replacing that with the temporary storage routing provides and then just selecting the right messages by querying the event stream for a specific address...