Not all repositories have a commits@ mailing list

A few places in the code assume that the mailing list commits@hostname.apache.org exists.
This is not always true, for example the www-site repository has the hostname www, but there is no such mailing list.
It's possible that there are other examples.

Also, what about retired projects? These still have websites, which may need to be redeployed.

Start by locating the code paths that assume commits@hostname.apache.org exists and compare their behavior with the www-site repository, whose hostname is www. Check whether retired projects with remaining websites are affected as well; done means identifying all affected cases and defining how deployments should handle repositories without that mailing list.

Written by the indexing model from the issue text.