It's essential that you don't drive you followers mad however, with promotional tweets, so do warn them about your promotion and mix up your tweets with your normal content. (writing.ie)
The article, which specifically focused on how the group has attempted brandjacking of promotional tweets sponsored by corporations, also contained a quote from Twitter's spokesperson Jim Prosser: (knowyourmeme.com)
Twitter, for instance, has only given the Senate intelligence committee a thumb drive of 1,800 paid promotional tweets from the Kremlin's English language Russia Today broadcaster. (thedailybeast.com)