Invalid certificate in outlook 2010 with 365 exchnage 1 are the affected outlook 2010 and outlook 2013 in the same network environment? 2 for ”2013 clients do not get this”, did you mean if configuring the same account in outlook 2013, you won’t get same errors in it? if so, i’d like to suggest you try the following methods to check if there is any improvement 1 clear the credential manager