You can download the version 1.3 of IBM Connections Mail in Greenhouse Catalog (Login required)!
Requirements:
IBM Connections 4.5 (+ mandatory iFixes – see IBM Connections support site) + IBM Connections 4.5 interim fix LO74571
One or more of the following:
IBM Lotus Domino 8.5.3 FP3 or later
IBM Domino 9.0 Social Edition
Microsoft Exchange 2007 SP3
Microsoft Exchange 2010 SP1