Exchangepedia’s post on controlling message size.

Outlook Web Access (OWA) has to be adjusted also if you are using this for large attachments. Couple links that outline this:

Microsoft Technet article

Microsoft Exchange Team Blog

Of course, need to add my 2 cents on this….

• If you increase your message size, the sending person’s mail server may not allow for these larger attachment sizes, so this needs to be taken into consideration.
• There are other ways of dealing with large attachment sizes – such as an FTP site or use some of the free ftp sending sites, such as You Send It that work quite well.
• Check your attachment file – is there something you can do to make it smaller? For instance..

1. Photos are generally by default fairly large and if you send several, the attachment size adds up. There are programs to resize these quickly (one I like is Irfanview – a freebie). Your photo editing software probably has a means of changing size also.
2. PDFs – Had an instance where the user was trying to send 30 MB PDF files that he had generated from a pdf creator plugin with an application. We ran this through PrimoPDF to create a MUCH smaller file of 1 MB and did not appear to lose anything that the recipient needed.
3. Word documents with images – Word docs often have screen prints of bitmap/BMP files. These can get huge if there are too many of them. With Vista and Windows 7, the snippy tool will create a small image… save it as a jpg or png file. If you have XP, you can use the free Snippy Tool.