Hello all

Running Exchange 2013 sp1 RU8. 

On our CAS servers we have configured our front end transport receive connectors with a  "maximum message size limit" of  150 megs, and "maximum recipients per message" with a 500 limit. Based on these numbers,  this mean an external sender can send an email that is 150 megs in size to 500 recipients. 150megs x 500 = 100 gigs. Does  this mean one email has the potential to increase the database size by 100 gigs?

Tha

Skipster,

No exchange will save the message once to my knowledge then just just reference that same location for all the mailboxes, so it really only takes up about 150 MB for the message.

This article might help you out some in making your decision on max values:

Large Message Processing in Exchange, Part 1: Prevention and Planning

Hi the article you mentioned is for Exchange 2007. From my understanding 2007 used single instance storage. However Exchange 2013 does not.  

Hi,

Yes, theoretically if these recipients are in the same database, then this database size will increase to around 150M*500=75G. Message is saved to per mailbox (150M per mailbox)

But this assumption is too extreme, because exchange will spend a great deal of time sending these messages. And the time of sending these messages depends on bandwidth.

So I dont suggest to increase the message size limit too large on send/receive connector.

Best Regards.

Hi Skipster,

Not sure what you meant "by Running Exchange 2013 sp1 RU8." Is it Ex2010 or Ex2013CU8.

Use below to check that and compare the results with Exchange Server Updates

Get-ExchangeServer | Format-List Name, Edition, AdminDisplayVersion

Setting the limit on just the connector doesn't necessarily mean that it will be sent to users as well.

There are other factors to be considered as well Scope of limits .

Order of precedence for message size limits

As said by Lynn, you should set more restrictive limits at the points where messages enter your infrastructure. For example, any message size restrictions on your Receive connectors that receive messages from the Internet should be less than or equal to the message size restrictions you configure for your internal Exchange organization. It would be a waste of system resources for the Exchange server to accept and process a message from the Internet that would be rejected by the Transport service on your Mailbox servers. Make sure that your organization, server, and connector limits are configured in a way that minimizes any unnecessary processing of messages.

Here is a link confirming your understanding on single instance storage unavailability for Exchange 2013.Which is similar to Ex2010.

Dude, Where's My Single Instance?

References:

Something similar to 150 MB message size, did you get the idea from here :p

http://blogs.office.com/2015/04/15/office-365-now-supports-larger-email-messages-up-to-150-mb/