Horizon Pharma ($HZNP) has officially begun mailing solicitation materials to shareholders of unwilling M&A target Depomed ($DEPO), including a letter related to its efforts to call the two special meetings it'll need if it wants to seal its deal. And should Depomed's investors need more information, Horizon has set up a website--www.HorizonAndDepomed.com--complete with details, stats and more. Release