In order to fix this issue: #550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##, you need to reset the nickname and the automatic completion caches in Outlook. How to reset the nickname and the automatic completion caches in Outlook http://support.microsoft.com/kb/287623 A very good third-party tool is Nir Sofer NK2Edit v2.03 http://www.nirsoft.net/utils/outlook_nk2_edit.html MCTS: Messaging | MCSE: S+M

After migrating some of our mail users from linux system to exchange 2010, we are have the folowing problems, when user with echange account try to send mail to non exchange user using auto complte they get the following error #550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ## Can anyone please help? Thanks in advance

In order to fix this issue: #550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##, you need to reset the nickname and the automatic completion caches in Outlook. How to reset the nickname and the automatic completion caches in Outlook http://support.microsoft.com/kb/287623 A very good third-party tool is Nir Sofer NK2Edit v2.03 http://www.nirsoft.net/utils/outlook_nk2_edit.html MCTS: Messaging | MCSE: S+M

Thnaks Jon, I will give it a try, one thing i will also like to clear up is we are exchange 2010 enviroment and migrated from outlook 2003 to 2010, moreover not all the user are migrated from the linux system. i will be very thankful for more INFO Best Jon