Are you trying to send or receive emails using Microsoft Outlook, but are you getting the error '21999'?
Microsoft Outlook is a mail application that is used to manage your email accounts. We can use it on Windows, macOS, and Android devices. This mail application was first released in 1996 and it has been developed and updated since then.
Besides email, we can also use Outlook for calendar management, contact management, task management, and notes management.
Outlook has different tools, such as the People button, the Mail button, the Contacts button, and other buttons. You can use these tools to manage your email accounts, calendars, and contacts with ease.
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On this page, you will find more information about the most common causes and most relevant solutions for the Microsoft Outlook error '21999'. Do you need help straight away? Visit our support page.
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It has never been easier to solve error "21999".
View list of solutions Contact an expertError information
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Category
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Error code21999
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ProductMicrosoft Outlook
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DeveloperMicrosoft
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Operating systemWindows 10, Windows 8, Windows 7, Windows Vista, Windows XP
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PlatformPC
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First seenJuly 25, 2021
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Verified-
How to solve Microsoft Outlook error 21999
We've created a list of solutions which you can follow if you want to solve this Microsoft Outlook problem yourself. Do you need more help? Visit our support page if you need professional support with Microsoft Outlook right away.
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Verified solution
You might encounter error code 21999 when you try to access your Microsoft Outlook account. This error occurs when there is an issue with your internet connection or if there is an issue with Microsoft Outlook on your computer or device.
Sometimes, this error can occur because of faulty memory chips in your computer or device. To fix this error, you need to try a few solutions.
Option 1: Make sure you're spending email from a single account (not a list or group)
If you're using a list or group, then you're receiving an error because Outlook cannot send email from the account that you're trying to send email from. You can change this setting in Outlook.
Option 2: Use an Office 365 Group
Office 365 Groups are a great way to manage multiple email accounts with ease, and we can also use them as a centralized place for managing contacts, calendars, and tasks all in one place.
You can create groups for your work or school accounts, family members, friends, and more! You can create multiple groups at once so that you can manage your email accounts all in one place with ease.
If you still receive an error, then try another solution below.
Option 3: Switch to a mobile hotspot
When using a mobile hotspot with your computer or device, then this can cause issues with Microsoft Outlook. The app uses internet connectivity, so try connecting through mobile networks instead of your home internet connection.
Pay attention also to the mobile hotspot network types, such as 3G, 4G, and LTE networks. If it connects to an unstable internet connection when you try to email, then you might receive an error message such as "Unable to send email" or "Error 21999".
Have you found a solution yourself, but it is not in the list? Share your solution in the comments below.
