SortingHat uses a very conservative approach to merging identities: it uses algorithms that are quite likely to only merge identities that really correspond with the same person. This approach is used because in production environments, experience has shown how erroneously merging identities causes much more problems than failing to merge some identities, and because it can more easily be complemented with manual curation of the data. For example, the naive algorithm of "merge two identities if the email address is present in both, and it is exactly equal", fails in large datasets for common cases such as "root@localhost", merging for example "John Smith <root@localhost>" with "Mary Williams <root@localhost>". SortingHat provides this algorithm, which can be activated, but we had to include a deny list with common addresses such as this "root@localhost" to make it useful. SortingHat periodically merges identities using these conservative algorithms, that can also be activated (or not) in its configuration. If more detail is needed, ingestion of identities **data** from reliable sources (such as company records, or FOSS Foundation **data** about its developers), or manual curation (usually via HatStall) can be used. However, since SortingHat offers an API to manage the identities it stores, more aggressive automatic algorithms for merging them could be easily implemented.