I have created a custom filter in https://stackexchange.com/filters and specified that I would like to get email updates:
However, I never got a confirmation mail nor any notifications based on my filter.
I tried the "resent confirmation mail" button on the right hand sidebar:
But again nothing happens.
The mail address should be fine
I used it for all kinds of notifications from Stack Exchange. For example the rep recalculation email arrived just fine on this address.
I retyped it several times to make sure there really isn't any typo
I double checked that it did not end up in the spam filter
I don't think it is a problem with my particular email provider, users with other mail providers seem to have the same problem, see Not receiving email confirmation on My filtered tags
This is possibly related to Tag subscription email not being delivered (2018–2019 edition), but this claims to be "status complete".
Although the "status-completed" tag was added, the problem still persists