Il faut exclure wlmail.exe des programmes qui peuvent utiliser sendmail sur le port 25 de votre antivirus notamment Mcafee
1.Go to Start->Programs->McAfee->VirusScan Console. (some may have 'Network Associates'instead of McAfee)
2.Double-click "Access Protection". On the left-hand side of the resulting window, select "Anti-virus Standard Protection" and on the right select "Prevent mass mailing worm from sending mail".Select the Edit button.
3.At the bottom of the resulting window is a section labeled "Processes to exclude :". Using the arrows, scroll all the way down to the bottom (you should see file names beginning with 'W' ). After the last entry put a comma and then a space and enter "WLMAIL.EXE" (without the quotes) and choose OK.
4.Now choose OK to close the properties window and lastly exit from the VirusScan Console.
You should now be able to send mail using Windows Live Mail. You may try restarting the computer after making these changes if the problem is not corrected immediately.