Friday, July 26, 2013

Exchange Active sync Message Size Limit

Hi Readers,

Sharing a small issue that has occurred in our environment as no admin have thought about it previously.

Message size limits that are set for our environment is 25 MB but some of the sales users  Complained that

they are not able to attach document to message that is more then 10 MB in size. We have tested this & found the same thing.

Issue was that in the web.config file (C:\Program Files\Microsoft\Exchange Server\ClientAccess\Sync)

<httpRuntime maxRequestLength="10240"/> was set to 10 MB.

We have changed it to 25600(25 MB) for resolving the issue.



Sukhija Vikas


  1. Thanks for posting this. Microsoft's documantation lacks a bit in this case, as they are only refenrencing to the files
    No word of
    There I found the 10MB limit and also increased it. The file was obviously modified by some Update, as it had a timestamp of some day in May 2015.

  2. Thanks for posting..It is working for me...

  3. Hi there,
    Thank for posting!
    I found this.

    3. ActiveSync
    When email is sent using the ActiveSync handheld device the message size is justified with the value located in the file %ExchangeInstallPath%ClientAccess\Sync\web.config

    Default Email message size in Activesync:

    (value in bytes) Approx 9.7 MB
    maxRequestLength="10240" (value in kilobytes ) = Approx 10 MB

  4. Thanks It works, The actual location for webconfig is
    C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\Sync

  5. HI

    we've made these modifications to the web.config file and increased the limit to 50MB, however we're still unable to send emails larger than 20MB from mobile devices (iphone/ipad)
    we have exchange 2010 btw

  6. have you checked what is the send/receive limit for email on exchange 2010 server ?? if that is 20 mb than this setting will not supersede

  7. thanks Vikas, all sorted now - we had to reset all limits again and now it's ok

  8. Patrick Roy LapratteMay 11, 2018 at 10:54 AM

    Yes, the path is wrong is the primary post.

    Thanks for telling us.

  9. Hi Jason
    where did you set all limits?
    in excahnge itself?

  10. Life saver man! Thanks for this post!