I've been looking all over for a relatively simple answer to a fairly straightforward question: "how do I increase the maximum size of attachments that can be sent and/or received in Exchange 2007?". But I have yet to find a solution that works.

We have a pretty straightforward setup: Exchange 2007 SP1 running on a single server, with the OWA role delegated to a second server. We did a clean install of Exchange 2007 a year or two ago: we did not upgrade from a previous version. I forget if we installed RTM and then patched it to SP1, or if we installed with SP1 already baked in. I just thought I'd mention those items, in case they influence the answer.

So far, I've tried running the following Powershell commands on the main Exchange server and verified that they've taken effect:

Set-TransportConfig -MaxReceiveSize 40MB
Set-ReceiveConnector "RcvConnector" -MaxMessageSize 40MB
Set-MaxReceiveSize "MailboxName" -MaxReceiveSize 40MB

As of right now, though, the specified mailbox is still rejecting messages over 10MB.

You get brownie points if you can also tell me how to set the default mailbox attachment size limits, so that new accounts don't have default Set-MaxReceiveSize values of "unlimited" they currently do.

Any advice or suggestions would be greatly appreciated. Tx in advance!