i am encountering this problem for a few weeks now with office 2011 for Mac. There is an error code: 17099: no local port.  I am not sure what this means. I had about 190 contacts in this group. I split them up into 2 groups, 1 has 100 addresses and the other has 90 addresses. Now the 100 recipient list sends out without a problem, but the 90 contact list shows up as an error. I contacted my ISP they said i have a limit of 400. I deleted the account off outlook and reset the account but i am still noticing the same error. I am not sure what the root of this problem is, if anyone could help, that would be great. Thank you!