CitiMortgage has done it for the very first time. The lender has reached out and partnered with Foxtons, a real estate Web site, in its first external marketing deal in an effort to find a quality stream of highly motivated borrowers. The lender has had active internal cross-selling programs with CitiBank and SmithBarney, but the alliance with London-based Foxtons is the first with a non-Citicorp affiliate “with any kind of great vigor,” said Pablo…