outlook Message "cannot send this item"

We are seeing the same behavior.  Disabling URL Rewriting may help future emails but does not fix emails that we already have in place and have been testing with.  

Following this thread.

We have encountered the same issue with 'Cannot send this item' errors appearing when replying\forwarding messages.

It appears to happen when the message content contains a chain of messages, which will have URLs in signatures that have been rewritten by Sophos Mail Gateway. One suggestion has been to turn off the URL rewriting but we have yet to test this.

I have, however, just tested a message from an eml file which was unable to send, and unfortunately the latest beta channel build 13919.20002 does not appear to fix this issue. The same 'Cannot send this item' appears.

What the root cause appears to be is either the number of URLs in the message body, or the combined length of all URLs - since rewritten URLs tend to be of a considerable length. I'm hoping to test this next by replacing previously rewritten URLs and testing. The combined length appears to be more likely as removing longest URLs first one by one until the message sends appears to resolve the issue with less removed than removing shorter URLs.

Many thanks,

--Richard Allan

Microsoft,

Please sort this as soon as possible, we are a small business and my other users are not tech savy so this is causing a lot of problems. I cannot believe how flaky the Microsoft products are now. Please stop changing things for the sake of change. I could go back to outlook from 1997 and have a better experience and be able to see folders down the side more clearly because they are colored yellow and stand out.

Please inform me when there is a fix and how to download it.

Hi to 

As of yesterday my outlook is popping the above message every time I try to reply or forward a mail as HTML. i even try to save the message and send it after but even that does not work.

Can you please help  

Meanwhile use below Work Around  :
Switch to Rich text 
Switch to semi Annual channel ( This is more stable since it get updated once in six month unlike current channel updated every month with new features  )
Remove the link in signature

send through outlook web app

The latest update is that a fix was implemented in build 13913.10000.  This build will get to the Beta channel (prior Insider Fast) likely next week in case anyone wants to test it.  At the current pace it should get to production in late April.  I can give a better ETA the closer we get.