Outlook - Sending mails dont work, but coming just fine

A few days ago I decided to move one, my important client, here on MXRoute and they have cca 80 accounts. All of them except few have an issue with sending mails. These accounts with the issue are with old PC and old Outlook versions (2003,2007 and one 2010). I have check ports if they are blocket, but all looks fine, but when I want to try to send get this error… here is image with result1

So in this case I think it’s that the first image indicates that an outdated copy of Outlook is attempting to use a version of SSL that is no longer supported, and the second image indicates that the ISP is blocking port 25 (notice it gives an IP after the 550 error that isn’t ours, and we don’t return message-less errors).

I’ve opened port 2525 on the server to attempt non-SSL over port 2525 to see if that helps.