Outlook sending error 0x800ccc1a sporadic and annoying

Copper Contributor

Good Day,


I'm really struggling with this at the office. It seems that only in Outlook 365 on LAN PCs that sometimes email sending isn't working and messages are getting stuck in the outbox with the error 0x800ccc1a (your server does not support the encryption type specified..). This happens all at the same time for all Outlook users.


We receive emails just fine.. but the funny part is, is that if we wait say 30min or so it will work again and the outbox will clear out. The encryption error goes away. During this period, all of our phones with Outlook and the same server settings on office wifi can send just fine through the same ports/encryption. And a period of time passes and the encryption error to the server comes up again.


I've tried just about every solution I can find online (and had to undo a few as it was so many different things it was overwhelming and have to backtrack).


The only thing I haven't had the opportunity to do so far is power cycle or reboot the Firewall/Router and that is my next step. ISP Fibre modem has been rebooted. It's difficultly finding the time to do this with so many of staff remoting in during COVID19...


Any solutions would be greatly appreciated. I've probably tried all of the bog standard ones you can find in the top 30 results on Google and forums again other than resetting the Firewall/Router. There doesn't appear to be any issues with virus protection/software updates/software firewall.



5 Replies

Just a quick update on this.. the cycle of the Firewall/Router and Modem didn't seem to work as the issue has re-emerged this morning. I'm wondering if it's possible if one of our office PCs is causing the issue for everyone.. stuck update, something configured in their Outlook. The only next solution I can think of is a good cold boot of all the PCs as well.


So frustrating..


I have had the same problem for many months. The problem comes and goes without me changing any settings. Rebooting usually fixes it, but it will also fix itself if I just leave it alone for a while.


I am very unhappy that Microsoft does not seem to acknowledge the problem. All solutions I have found online have been useless.


Its 2023 and I have the same intermittent issue. It has been going for months. Multiple online sessions with Microsoft support have done nothing, third-party software does nothing and I still cannot find a solution online. If you found a solution (other than migrating to Gmail or Thunderbird) I would like to know.


As best I can tell, this has something to do with Outlook not realizing that my wifi has set a new connection. Outlook seems to be trying to use an old connection that eventually times out. Seems especially to be a problem when my computer has resumed after being asleep.


The work around I have found is to left-click the wifi icon on my task bar, then click the wifi box to turn off the wifi and then click again to turn it back on. Outlook is then able to find the new connection. If I do this before opening Outlook, I never have the problem. It's a bit of a hassle, but much quicker than having to wait for Outlook to timeout.


Outlook is the ONLY app that seems to have this problem. This is a glaring bug that should be easily fixable, and it is appalling that Microsoft does not acknowledge it and fixed it.

Thanks for the suggestion. Disconnecting and reconnecting the wifi is much faster than waiting, or rebooting. As you say, it reduces the symptoms but does not address the cause. It is a 'smart' company like Microsoft can't identify or fix it.