The Send Later function is hidden under the little down arrow by the Send Email button and will be available to Office Insider Fast members now and Office 365 subscribers in July. All other new features should be ready for Office 365 subscribers right away, including the easier onboarding process, which automatically detects your email settings from your address so you don't have to, and read receipts, which may be the bane of our existence, but seem to make business users pretty happy. This brings Outlook 2016 for Mac up to parity with Outlook 2016 for Windows, which already has.
Synchronization usually occur for all outlook email folder when server was restarted or went offline and upon staff logging to email. This is normally automatically done by Outlook behind' [/quote].
In addition, users can so similar things with extensions and built-in features, as well. Goog'es business-flavored G Suite allows administrators to enable, third-party can let you schedule your emails and the even your basic Gmail account can Google Calendar events on the fly. Still, it's got to be great to finally be able to schedule your emails or find out if they've been received when you're using Outlook on the Mac.
Consider clearing or archiving folders where mail is automatically being placed. After trying many things (like clobbering old directories in Caches, Preferences and Containers) with only minimal benefit, I had some success by clearing out some subfolders that I don't pay much attention to, where I have less-important mail refiled by server-side rules. When those folders had around 10K messages in them, I saw mail get stuck 'Downloading messages' forever, not pull in incoming Mail for hours (until restart), or simply crash occasionally. I haven't seen any of those since clearing out that clutter, knock on wood.