This doc DOES note Mode Conditioning cables
http://h18000.www1.hp.com/products/quickspecs/12280_div/12280_div.pdfAs the core diameter of single mode is much less than multimode, there is no optimal optical contact between the SFP and MM fiber.
But the transmitter will still send light into the cable.
And the receiver will recieve light.
The further you get to the 550m (MM) limit the better it will work if you DO use mode conditioning cables.
For short distances it will work without.