Hi all I have a brand new Imac Pro running mOjave 10.14.2. Super fast internet connection (via ethernet), not wifi. I installed Outllok for mac, latest version, I set up my 2 exchange accounts, and whenever I send an email, it takes a looot of time to actually send it out. (more than one minute for 158kb attachment). I have uninstalled Outlook, remove accounts, add accounts, etc....nothing worked. Microsoft support is looking into it, but all solutions they provided (actually check date and time settings and changing the MTU size under network preferences- System Preferences -> Network -> Advanced -> Hardware -> Change the configuration to 'Manual' and change the MTU 1458. https://support.zen.co.uk/kb/Knowledgebase/Changing-the-MTU-size-in-Mac-OS-X-10.6-to-10.9 ) Thanks for your support.