Bitbucket unfortunately has a number of uneducated and inconsiderate users who like to spam the rest of us by commenting on issues with things like "+1" rather than using the proper voting function. These comments add no value and everyone watching the issue gets an email (quite often hundreds of people).
Please prevent users commenting with just "+1" -- requiring at least 10 characters would be one solution (as per e.g. StackOverflow).
Even better - suspend user accounts for 24 hours that try; that should put a stop to it promptly.
This will help make Bitbucket a better service for its dedicated users.