Outlook: Cannot Send This Item

Published on Tuesday, October 25, 2011 in ,

A customer of mine was struggling with the following error in Outlook:


Microsoft Outlook: Cannot send this item

It started appearing after they introduced a new Exchange 2010 infrastructure and had migrated some pilot users from their Exchange 2003 environment. At first the repro we found was: start a new mail, type some random stuff in it and then wait. After some time (10 – 15’) hit send and see if you get the error. Now that was really lousy to reproduce…

On the internet we found a workaround: whenever the error would popup, you can choose the “Format Text” tab en switch between HTML and Rich Text. Then just hit send again.


We weren’t satisfied though, because of this formatting workaround we were suspecting a problem with the html of the signature in the mails. We found a hotfix regarding GIF images and outlook but that didn’t seemed to solve it. Besides that, our issue wasn’t always reproducible and time seemed to be a factor… So we shifted away from the formatting issues and looked further.

After some network tracing, lots of coffee and patience we seemed to have found the culprit. By clicking right on the outlook tray icon (while holding ctrl down) you can view some connection statistics:




The picture is a bad example as I’m actually disconnected, but you get the idea. What we were seeing was that we had quit some failed requests. However this wasn’t really noticeable in the Outlook from the user point of view. Now we could reproduce our problem by opening several mails and just waiting until a failure popped up in the statistics. After such a failure we couldn’t send any of those mails we had open.

Once we learned this, we involved some networking guys to check all involved devices: firewalls, load balancers, … and they found out some device was malfunctioning (dropping packets).

Summary: if you are hitting the “outlook cannot send this item” error. Don’t go for the easy workaround by learning your users to change the format back and forth.  In stead do some troubleshooting and check the health of your network, at least if you are seeing connection failures in the statistics…

Related Posts

9 Response to Outlook: Cannot Send This Item

09 August, 2012 01:17

Very helpful, thanks!

22 April, 2013 06:23

I have the same problem, I'm using POP3, I haven't Exchange, is connection status only for exchange? because I can't see details for my connection

22 April, 2013 06:24

I have the same problem, I'm using POP3, I haven't Exchange, is connection status only for exchange? but I can't see details for my connection

25 March, 2014 23:16

outstanding, I've been looking for an answer other than "switch to rich text". My suspicion had been that it was an update missing, but that didn't seem to fit from what I was finding.
A network issue makes perfect sense as to why only very select individuals would have the issue. As it turns out the 2 users I had with this issue had Linksys switches to split their line to a printer. Replaced switches.
Thank you!

18 August, 2014 18:46

I only have this issue with email dated prior to joining Microsoft Exchange. Anything in folders from pop3 mail is not recognized by the exchange server. Have to cut/past from pop3 email to Exchange Svr. I don't know the answer if you have a lot of this going on.

11 October, 2014 01:03

Did not work. Had to save the attachments, create a new e-mail message and attach the files to it. Then it was sent without hesitation.

30 June, 2015 19:24

In depth post, thanks.

17 March, 2016 20:10

I find that if you wait 30 seconds and try to send it again, it goes. I find that it only happens when I use the "Attach to e mail" option from within the pdf document. If I close up the document, then open a new email, and attach it when it is closed it doesn't happen. Just my two cents.

25 September, 2019 07:39

I came across this issue yesterday. Windows 10, Outlook 2016 (16.0.11929.20234) 32-bit, on-premises Exchange 2010, no Cached Exchange Mode, with an image used in the signature. Removing the signature allowed emails to send, but with the signature included we saw "Cannot send this item".

Another confirmation here that turning on Cached Exchange Mode fixed it.

Glad I spotted this thread!

Add Your Comment