Wednesday, August 26, 2009

Entourage EWS Attachment Limits

We've been wrestling through an Entourage attachment-size issue that's been maddening. Today we finally got to work with Microsoft's Product Support Services technical lead. He and his colleague were helpful, and we got through it, but it took more than an hour! It was about as straight-forward as San Francisco's Lombard Street, but here's what we learned:
  • Entourage file attachment limitations are managed by the Exchange 2007 server in the EWS folder.
  • There's no easy-to-use checkbox to say someone has no limitation on attachment file size.
  • Assuming that when you don't impose an attachment size limitation on a user-- presumably because you don't want there to be a limitation on their attachment sizes-- is enough won't work. Exchange applies its default limitation of 5mb!
  • When setting a higher limit to allow someone to send attachments larger than 5mb, don't base the new limit on the actual size of the attachment files. Mime will expand attachments about 1/3 larger than their original file size. But don't base the new limit on that size either, because Exchange expands the attachments even larger! Set the limit to about double the original attachments' file size.
Many Mac users work on media files. While email isn't the best way to send large files, some will want to quickly send large (25-50mb) attachments. Microsoft will be wise to simplify this process.


Gary Messmer said...

Here’s the technical instructions…..

In addition to running the appropriate cmdlets to change message size limits in Exchange, you'll need to edit web.config found in C:\Program Files\Microsoft\Exchange Server\ClientAccess\exchweb\ews. Open with Notepad (or your favorite text editor) and search for maxrequestlength. Change the value to reflect the size in kilobytes desired, then save the change.

For good measure, edit web.config located in C:\Program Files\Microsoft\Exchange Server\ClientAccess\owa.

Once both files have been edited open a command prompt and run the following commands:

cd \Windows\System32\inetsrv

appcmd set config "Default Web Site/ews" -section:requestFiltering -requestLimits.maxAllowedContentLength:[size in Bytes!]

appcmd set config "Default Web Site/owa" -section:requestFiltering -requestLimits.maxAllowedContentLength:[size in Bytes!]


Note: replace [size in Bytes!] with the actual number of bytes based on the settings you chose for the web.config files.

After IIS has restarted you should be able to send large attachments; just like a Staples Button - That was easy.

Hope this helps someone else.

Anonymous said...

Oh thanks for this. Have been very frustrated to get to the bottom of this, with both Entourage and the new Apple Mail clients both failing to send larger attachments hinting at something in EWS settings. I hope others that might be searching for something on setting Exchange 2007 EWS attachment size limits will find your posting faster than I did!

-- Alex

Nick Nicholaou said...

Thanks, Alex, for your encouragement. I just posted the link in the Mactopia Forum to help folks find this post easier.

Anonymous said...

Any idea on how to run the equivalent 2 appcmd lines in an IIS 6 environment? AppCmd is IIS 7-specific.

Anonymous said...

I'm also running IIS 6 rather than 7. I found that just changing the value in web.config and then running iisreset fixed the problem, no need for any "appcmd"-equivalent tricks.

Anonymous said...

I tried this and still cannot send file attachments over 10 MB or so with either entourage or mac mail on snow leopard. With Mac mail it times out and with entourage it gives a http error. Any other suggestions? After looking into this on the Apple support forums it seems to be a pretty common problem.

Anonymous said...

Update for above. It seemed that for me restarting IIS was not enough. I ended up rebooting the server so there must be another service that needs to be restarted.

Anonymous said...

For SBS 2008, the OWA is hosted by "SBS Web Applications", not Default Website. I received an error when I typed "appcmd set config "Default Web Site/ews" -section:requestFiltering -requestLimits.maxAllowedContentLength:[size in Bytes!]" but it did not error with "appcmd set config "SBS Web Applications/ews" -section:requestFiltering -requestLimits.maxAllowedContentLength:[size in Bytes!]"

I haven't tested that the problem has been fixed though.

Anonymous said...

Hello there,

i edited the 2 Files, and restartet the Server, now i have a big problem.

All Apple Mail Clients cant connect to my server anymore...

The server returned the error: The connection to host my.server.local on port 443 failed.

Any Ideas? dont know an solution

All other Clients work great...

Anonymous said...

problem solved!

works greats, thx : )

Andrea said...

Hi there,
great post...but...sorry for this question...i cannot find appcmd command in my windows server 2003 (with exchange 2007, hub transport server) into the inetsrv directory.
Could someone help me pls?


Anonymous said...

Andrea, Someone else running IIS6 (Server 2003) commented above that only the edits are required, followed by an iisrestart command. Try that and post back if you still have problems.


Anonymous said...

Thank you for your quick answer!
So, these are the steps i made:
- Edit the EWS and OWA web.config file, with the new value; iisreset
- It worked sending attachment of 9 Mb with Entourage and from INSIDE network (we have a cisco firewall to connect to internet)
- From outside network (with HSDPA key) is working ONLY with Entourage 2008, but not with Mail.App , that is giving me back the message with the error about sending the same message.
Any ideas?

Andrea said...

Previous post by mistake sent as anonymous...Andrea is writing ;-)

Yalikins said...

I had done this fix two months ago and it worked great. Applied exchange 2007 sp2 and it reset my values. Couldn't be a flunky to notice, had to be the CTO...

Anonymous said...

In my testing you have to double the size of the file max file size to get it to work as expected.

<httpRuntime maxRequestLength="30000"

this will allow a 15MB attachment


Anonymous said...

Hi, on MS Exchange 2010 I have the same problem with entourage clients.I try what is describe in this forum but, when i restart iis, entourage can't receive and send e-mails.I change "maxReceivedMessageSize"
parameters on bindings chapthers, restart iis and all work fine.

UroŇ° said...

Thanks! Works great on SBS 2008, but you have to follow some changes for specific IIS COnfig on SBS 2008:
SBS 2008, the OWA is hosted by "SBS Web Applications", not Default Website, so you have to put:
appcmd set config "SBS Web Applications/owa" -section:requestFiltering -requestLimits.maxAllowedContentLength:51200000

Thanks, again for this explanation and instruction how to correct this.

Uros Lesjak, from Slovenia

Jordan said...

I ran into this today on our Exchange 2007 server running on Windows Server 2008. I set the maxrequestlength size to 100000 just to give breathing room. I didn't use iisreset or appcmd, but used the IIS Admin tool to restart the web service. After that, the large attachment went through with no problems. Thanks for the help!

Jordan Klein

Anonymous said...


I'm having the same issue with my exchange 2007 installation but I can't find the maxrequestlength option in the ews web.config. It seems I'm the only one having this trouble, do I need to create the config line? or maybe the /owa modification is enough?
thanks for your help


Gary Messmer said...


No clue why you can't find that. I checked an Exchange 2007 server today and found that in the (system.web) section - here's a snippet:

(httpRuntime maxRequestLength="[size in KB]" /)

Remeber to change [size in KB] to the actual number!

Hope that helps, post back to let everyone know!



David said...


I can only find the value maxrequestlength in the ews and owas web.config.

I use IIS6, Winwdows 2003 and Exchange 2007.

I have changed both values to 100000, but i still can´t send more than about 13 MB´s from Entourage EWS... ( i have restarted the server)

Anonymous said...

I will try this later.
So as i can read here, if i want to sent files with the size of 50MB i must set the size to 100000???
In exchange itself you can set permissions to the mailbox for the file size, is this setting over rulling this setting?
So i want a user sending files not larger then 20MB and change the permissions in Exchange on his mailbox, is he able to sent file till 50MB because of the setting for maxreuestlengt is 50MB??


Andy said...


Ok, new twist on this problem. I too struggle to send any emails with the smallest of attachments via Mac Mail using Exchange 2007. I receive mail slow but ok (although the Exchange Account does beach ball alot when checking for new mail) but replying or sending is a nightmare.

I am using Mail 4.4 on Mac OS X 10.6.6 on an iMAC. We use Exchange 2007 and it's run and managed by Microsoft "Microsoft Business Productivity Online Standard Suite" We are not allowed to change server settings. I am the only one in a small, remote-workforce company that lives in the UK and I keep being told that is the issue. I've found too many people with similar problems on the web to believe that, but I haven't found an answer. Any ideas??

Gary Messmer said...


Read the MS provided documentation here;

I noticed a few things in the docs, for example; a list of supported client apps (Mail is not included in that list) and Microsoft imposes a 10MB max message size.

Since this is a hosted service and out of your control, try using once of the supported applications as you may get better results.

No harm in requesting Microsoft change things, too!

Hope that helps!



Jason said...

Hi Gary...Thank you so much for the above post...But, I cannot find the Max request length in the ews web.config file. I can find it in the file under owa..but not ews.

also, I run Exchange 2007 on Windows server 2003 and IIS6. How can I get the appcmd working. It says that appcmd is not recognized as internal or external command. do I need to use Shell? If yes, please let me know the command

Thanks for all you do.


Anonymous said...


We've moved on to 2010 but I took a quick look at a client site running a similar configuration to what you described; Server 2003, IIS6 and Xchange 2007. Here's what I found:

maxRequestLength is in the section of the web.config file. File location is C:\Program Files\Microsoft\Exchange Server\ClientAccess\exchweb\ews.

You're right about appcmd - that shipped with IIS 7, not included in IIS 6. Someone else replied that everything worked properly after making the edits and then doing an iisrestart (or maybe just restart the server.)

Hope that helps, post back and let us know - it could save someone else innumerable hours!

Anonymous said...

Thanks to Yalikins who explained that the default of 30000 allows 15MB so I doubled simply the defaults in bot web.config files. On myself I had calculated too big numbers, maybe beyond the limits set in the Exchange Management Console, which yield me an unknown Outlook error on the client. Editing the config files and iisreset worked fine for my EX2007 on Win2003 server.


john-mac said...

we also have this problem on outlook 2011, i have changed all the setting microsoft / others say to change up to 50mb and cant email out passed 12/13 mb.

Ned Ludd said...

We use IIS6 and so have only edited the web.config files as recommeneded. IIS has been restarted and this appeared to resolve the issue but only for a short time.

The maxrequestlength had not reverted so we are unable to see why this stopped working again.

Anyone else experienced this?