Can't open Outlook Email on Safari: says "server unexpectedly dropped the connection."

Hello sterling279,

Thank you for reaching out to Apple Support Communities, and we'll be happy to help in any way we can. We understand you're having issues with opening a webpage in Safari. Try the steps here to see if they resolve the issue: If Safari on Mac doesn't open a webpage or isn’t working as expected - Apple Support

"If Safari isn't working as you expect, one of these solutions might help.

These solutions are for issues that affect Safari on Mac, including issues such as these:

• A webpage is blank, doesn't show all of its content, or doesn't work as expected
• You can't sign in to a webpage, despite using the correct sign-in information
• A webpage asks you to remove or reset cookies
• Safari slows down or stops responding

Solutions for Safari on iPhone and iPad are also available.

Reload the page

To reload a page, choose View > Reload Page, or press Command-R. If you can't reload, make sure that you're connected to the internet.

If you still can't reload:

1. Press Command-Q to quit Safari. If Safari doesn't quit, press Option-Command-Esc to force Safari to quit.
2. Open Safari again and try to load the page. When Safari opens, if it automatically opens pages that you don't want to open, quit Safari again, then press and hold the Shift key while opening Safari. 

Check Safari extensions

If you installed any Safari extensions, make sure that they are up to date.

You can also try turning extensions off. From the menu bar in Safari, choose Safari > Settings (or Preferences). Click Extensions, then deselect the checkbox for each extension to turn it off. Learn more about Safari extensions. 

Check Safari settings

The webpage might not be compatible with one or more browser settings, which you can turn on or off as needed. From the menu bar in Safari, choose Safari > Settings (or Preferences). Then click Websites, Privacy, or Security to access these settings:

• Websites settings. These settings can be configured for specific websites.
• Privacy settings. These settings apply to all websites.
• Security settings. These settings apply to all websites. 

Test with a private window 

A website can store cookies, caches, and other data on your Mac, and issues with that data can affect your use of the website. To prevent the website from using that data, view it in a private window. From the menu bar in Safari, choose File > New Private Window, or press Shift-Command-N.

If that works, use the following steps to remove the website's data, including its caches and cookies. The website can then create new data as needed. If it's a website that you sign in to, make sure that you know your sign-in information before continuing.

1. Choose Safari > Settings (or Preferences), then click Privacy.
2. Click Manage Website Data.
3. Select the affected website from the list shown.
4. Click Remove.
5. Click Done.
6. Open the website again in a non-private browser window.

Install software updates

Install all available Apple software updates, which can include updates for Safari.

Check VPN or other security software

If you installed VPN or other software that monitors or interacts with your network connections, that software could affect your use of the website or the internet. Learn about network issues related to VPN and other software. 

Check network settings

Certain network settings, such as those related to using a proxy server or custom DNS server, can affect access to content on the internet. Even if you haven't changed your network settings, you might have installed software that changed those settings for you.

To find out whether the issue is with the network settings on your Mac, try viewing the website from some other device connected to the same network.

To find out whether the issue is with your network itself, try viewing the website after connecting to a different network.

Resolve other issues

• If Safari appears to be stuck on an unexpected homepage
• If you want to block pop-up ads and windows
• If you deleted Safari and don't have a backup, reinstall macOS to put Safari back in your Applications folder. Reinstalling macOS doesn't remove data from your computer.

If you still need help, please contact Apple Support."

We hope this helps.

Cheers!

(1) you may install "Thunderbird" email-client, alternative of apple's "Mail" email-client.

(2) it should work fine ... but if you see Thunderbird is also displaying message, that .. Server busy or connection dropped ...

then,

(3) goto Thunderbird > Account Settings > select your outlook account > Server > find the line "Check for new messages every [15] minutes".

(4) ... change that 15 into 25 minutes, now it should work ...

( for "Yahoo", that field value often needs to be 50 minutes, in some computers or for some users )

(5) when you have too many accounts open in same website or mail-service , from your home / office / LAN etc

(6) ... or when you enabled too many IMAP folders monitoring ... etc ...

(7) then such message can be shown to user.

(8) Some network device in your LAN side is causing network packet related problems, ...

(9) ... it could be DHCP related , GW adrs conflict , etc, etc

(10) ... you can diagnose network traffic (with WireShark, etc, etc monitoring tools & commands) to understand/detect more on the problem if you know about computer networking addressing, packets, protocols, etc etc.

(11) Mac computer's network settings have option to turn on PROXY (aka: Limit IP-Address Tracking protection, etc )

(12) ... turn that off in mac

(13) ... turn-off such option inside Safari & Mail too

(14) ... then try again

(15) ... then fine-tune those proxy settings again later, to set it ON where you need & set it OFF where you dont need.