Twitter mentions in promo-tweets are simply a nice way to recognize and thank the "news spotters" who have contributed to your paper.
How mentions are chosen by Paper.li
The mentions in a promo tweet are selected by us at the time your paper is updated and will be a news spotter from anywhere on your first page of your paper.
We have a rule that eliminates any news spotter from being mentioned twice within a 48 hour period. Therefore, if all of your news spotters have already been mentioned in another paper.li promo tweet within the past 48 hours, we will not place any mentions in a promo tweet.
Additionally, it is also possible for a "news spotter" to opt out of being mentioned in promo-tweets. If they have placed themselves on our "no mentions" list, we won't place them as mentions in Paper.li promo-tweets.
Mentions may vary from the example mentions shown in settings
When you view the default promo-tweet or customize your tweet, we will show you example mentions. The mentions shown in the displayed tweet are examples only and may not necessarily be the same mentions that will appear in the final tweet at the time your paper updates.
Why? Because between the time you modified your tweet, edited your paper and/or re-fetched new articles, it is possible that the @username has already been mentioned in another paper.li promo-tweet or is no longer found on the front page of your paper.