(ShareCast News) - Marketing emails specialist dotDigital has posted a 29% rise in half-year revenues to £12.9m driven by its US operations.Monthly recurring revenues from its dotmailer "software as a service" platform was up approximately 35% to £10m, the firm said in a trading statement.Creative and managed service email marketing revenues grew by 36% to £1.5m, while average revenue per client grew by 31% to £525 per month from £400.The total number of emails sent by the dotmailer platform soared by 50% to 3.9bn from 2.6bn.The company said US region revenues were up approximately 84% to US$2.1m from from $1.14m, while expansion into Mid-and-West coast America was "starting to deliver good channel partnerships and direct sales opportunities".It added that Australia was now a key growth area with six key channel partners there producing a strong sales pipeline.