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Message Size Limits

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  • Message Size Limits

    This one’s got me scratching my head. Any help / advice will be much appreciated.

    Environment – Exchange 2003 sp2 + all updates both exchange and windows. Front end / backend setup with the backend being a two node cluster.

    I’m controlling message size limits through Global Settings -- > defaults.

    Our current Sending/Receiving Message size limit is 10240 KB (10MB)

    One of our execs insisted he needed to be able to received emails attachments which are 13MB (I don’t like the idea, but he’s the boss).

    If I set the message size limits to 13MB or even 14MB external messages do not come through. Email bounces at the other end giving a message along the lines of message too big. Internal email works just fine.

    It’s not until I set the Sending/Receiving Message size limit to above 16384 KB (16MB) that messages will come through from external clients.

    I tried testing larger attachments and the same thing happens. Lets say I want to enable maximum message size to 18MB. I have to set the Global Settings -- > defaults --> Sending/Receiving Message size limit to over 24MB before external emails will come through.

    It’s very strange. I know there are a lot of places were the message size limits can be set however the fact that I will get messages as long as I increase the limits to more that what I want in the global settings works makes me thing this is something different.

    Thanks in advance.

    Last edited by quinla01; 20th September 2009, 11:54.

  • #2
    Re: Message Size Limits

    There is always some overhead with attachments, for the encoding. Depending on the format of the message and the attachment this can vary. Therefore setting a 10mb limit will not allow you to send a 10mb attachment. You also need to take in to account the body of the message.

    The size that you have needed to set though seems a little high, which would tend to indicate there is some additional bloat somewhere - disclaimer, something like that.

    Simon Butler
    Exchange MVP

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