Right now, the only tag available on docker hub ist latest.
This makes using MailHog from docker hub risky.

That is,
docker run mailhog/mailhog:latest
might return a different image on every call.

However, for example,
docker run mailhog/mailhog:0.2.1
would return the same image on every call. This would make builds relying on MailHog repeatable and deterministic.