After {T173475} was deployed. It was discovered T177825 that the block list was storing zeros (or a set of zeros) in the database.
Originally it was assumed this was a result of the deployment and maintenance script T178313, but that does not appear to be the case.
Here is a query to see the rows that are bad:
```
SELECT * FROM user_properties WHERE up_property = 'echo-notifications-blacklist' AND up_value REGEXP '^(0|0\n)+$';
```
Here is a query to determine the valid rows:
```
SELECT * FROM user_properties WHERE up_property = 'echo-notifications-blacklist' AND up_value REGEXP '^[^0](.|\n)+$';
```
The number of bad rows has been increasing over time.
There are a significant amount of rows that are an empty string:
```
SELECT * FROM user_properties WHERE up_property = 'echo-notifications-blacklist' AND up_value = '';
```
However, these rows existed before T173475.
Ideally, if the user does not have a echo notification blocklist, then the row should not exist at all (i.e. `null`)