Cannot attach large attachments although server settings would permit that

attachmentexchangeexchange-2010outlook-web-app

we're currently have some weird issue with our organization's Exchange Server 2010:

Although on the server the attachment size is set to 55000000 bytes in the web.config file for OWA, users cannot attach files larger than approx. 25 MB.

Here's some more details and steps to reproduce (screenshots are in German…)

  1. Open OWA web page

  2. Log on using AD credentials

  3. Create a new mail
    new mail window of OWA

  4. Click the paperclip icon (add attachment)

  5. A Common Dialog (FileOpenDialog) is shown

  6. Select a large file (approx. 30 MB) to upload and start the upload.

  7. after some seconds, an error message is shown:
    action couldn't be completed error
    (English: The action you tried to perform couldn't be completed because there's a configuration problem on the server. If the problem persists, please contact Helpdesk.)

  8. Any ideas, why this message is shown? It doesn't explicitly mention any size limit being exceeded… But strangely, smaller files can be attached without any problem.

Some additional information:

  1. Upload attachment after above error message

a) Sismiss dialog box and click the paperclip icon once again)

b) Strangely, now there's a different dialog box being shown. Now it's not a Windows dialog box anymore, but a HTML element:
different attachments upload dialog

(The German text does not really matter. It more or less explains how to attach a file. The button "Durchsuchen…" ("Browse…") lets the user select a file and the link "Anfügen" ("Attach") attaches that file to the mail.)

c) Now, the file can be uploaded without an error message being shown. (File size: 25 MB)

  1. Upload an 40 MB ASCII Text file (only characters A-Za-Z)

a) create a new mail

b) click the paperclip icon to attach a file and select a 40 MB ASCII text file.

c) Start the upload.

d) The following error message is shown:
message exceeds maximum size error
(The message box says: The following files weren't attached because they exceed the maximum size limit for attachments (40 MB): char42. ) [or similar]

e) When seeing this error message, it is clear that the attchment size is to high.

–> Why is that message shown here, but not in the 25 MB binary file as mentioned above.

–> The size limitation is set to 55000000, why is then 40 MB shown in the error message?

Did anyone already see a similar behaviour?

Does anyone know how to fix this issue and to be able to upload (binary) files larger than 25 MB?

Best regards,

Tom

PS: I asked the same question also on Technet (Technet Link)

Best Answer

I mixed my first answer up.

Go to Organization Configuration, Hub Transport, Send Connector tab. Right-click your send connector, go to Properties and set the Maximum message size to 55000 on the General Tab.

Next, go to Server Configuration, Hub Transport, and under Receive Connectors, right-click the receive connector and go to Properties. Under the General Tab, set your maximum message size to 55000.

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