How about to a new optional Cabal field like "mail-report"? (don't bother about this name, I chose it randomly)

 

If a build failure happens, or there is some relevant information about your package, Hackage will send a mail to the direction specified in that field. A field which content will NOT appear in the package page, so internet bots can't record so easily your mail direction to send you real spam. This is the reason because I write my direction in the "name at domine dot com" form (since a while ago), in spite of I would really like to receive mails about fails in those packages I maintain.

 

Furthermore, since the field would be optional, you still can avoid to receive these mails.

 

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Daniel Díaz