Hello, We run Exchange 2007 with 2 CAS servers, 2 Hub Transports and multiple Mailbox servers. We've been experiencing some intermitten problems with OWA and Entourage. On occasion users of Entourage seem to get an error message that states the following: Error HTTP Error. The post data is too large. Explanation Mail could not be sent. Message has been moved to the Drafts folder. Error: -1 In the W3SVC logs in IIS on the offending CAS server we get this error message: 2008-06-17 12:53:05 W3SVC1 10.30.64.36 POST /exchange/<username>/##DavMailSubmissionURI##/ - 443 - 1.2.3.4 Entourage/12.10.0+(Intel+Mac+OS+X+10.5.1) 413 0 0 (Username and password have been masked for privacy reasons). Did some googling and 413's 'usually' have something to do with UploadReadAheadSize. However, we've played with a bunch of settings for this, including setting it to 65535, but we still get the same error. Has anyone else experienced this problem? Thanks! Warren

Warren, Does the message really get moved in to the Drafts folder? Is there anything special about the message such as a long subject line? Special characters in the subject line? A large message? Thanks, Jim

Jim, Yes, Entourage does move the message to the drafts folder (I'm presuming locally and not onto the Exchange drafts folder). Typically if you try again, it usually succeeds. It definately has something to do with the 413 Error in the IIS log above, but i'm baffled as to what it means. No special characters in the subject line, but it appears to occure the most when there is an attachment, size doesn't appear to matter - a couple of kb to a few hundred kb. Warren

I am having the same issue. Mac users get error messages when sending email via Entourage.Error:HTTP error. The post data is too large.Mail could not be sent. The message has been moved to your drafts folder.Error: -18587Actually the email and attachment is only 200kb.The exchange server 2003 (sp2) is working well with outlook and OWA. But just a few people using MAC and Entourage will get this error. And if they try a few more times, the email might go through. It's quite annoying. Don't know why.

I had this problem after I changed the SSL settingsfor OWA and AutoDiscover in IIS Exchange server 2008. Changed settings back and problem went away. Look at your IIS manager and SSL swettings for OWA (take screen shots) and try different settings.

Had a similar problem with Entourage: 13.0.3 Web services edition and Exchange 2007 SP1Users got: ERROR HTTP Error. The server cannot fulfill the request. Explanation Mail could not be sent. The messege has been moved to your Drafts folder. Account name: "xxxxxxx" Error: - 18500Had to edit web.config (...:\Microsoft\Exchange Server\ClientAccess\exchweb\ews) and add <httpRuntime maxRequestLength="30000" /> after <system.web>, restarted IIS and that actually fixed it.

It looks like this problem is back with Outlook 2011!!!

It looks like this problem is back with Outlook 2011!!! Same here with Outlook 2011. Can't believe it's back..... Error code: -18587

Hello, I'm using Outlook 2011 and still having the 18587 error code. After I try to send an email, the error message appears and the email its moved to the "Drafts" folder. Then when I re-send it, it goes fine... Does somebody find the solution? Thanks.

Any news ? or better a solution ? We have +50 macs (Entourage 2008 EWS/ Outlook 2011) connected to Microsoft BPOS seeing this issue randomlly.

According to Microsoft Support. MS Online Services doesn't support Outlook 2011 yet. (until spring 2011) However they send me this link: http://social.technet.microsoft.com/Forums/en-US/onlineservicesexchange/thread/4f0cb239-738b-4c90-b628-e6dd64a58916

Dear all, has the problem been solved or workarounded meanwhile? We are getting this error every now and then: HTTP error. The post data is too large. Mail could not be sent. The message has been moved to your drafts folder. Error: -18587 Best, Tim

Has anyone heard anything more about this? We're still having the problem and have multiple tickets open hoping someone can solve it. It looks like they moved us to a different server but with no luck - we're still getting the error. Is this only a BPOS issue or are people seeing it on other hosted exchange providers? MS needs to get it solved! Don