Correct. When I worked at MS I believe the bloat could be upwards to 30%, but 1.4*attachment limit is a good formula.
Here is an article on increasing the attachment size within EWS: https://social.technet.microsoft.com/wiki/contents/articles/3954.allow-large-attachments-for-ews-clients-such-as-entourage-and-mac-outlook-2011.aspx Just in case anyone has the IMMENSE pleasure of supporting Outlook for Mac. From: [email protected] To: [email protected] Subject: RE: [Exchange] Quick straw poll: Email size limits Date: Wed, 18 Dec 2013 10:57:52 -0500 Right on – A current approach could be to advertise 25 MB as the limit and actually set the limit to 1.4 * 25 MB = 35 MB. To account for the factors that Adam mentioned. Mike From: [email protected] [mailto:[email protected]] On Behalf Of Adam Farage Sent: Wednesday, December 18, 2013 10:50 AM To: [email protected] Subject: RE: [Exchange] Quick straw poll: Email size limits For most of my customers, we do 25MB. Some customers that are heavy on Outlook for Mac we set it a bit higher due to the ASP.NET to SMTP transcoding bloat.> Date: Wed, 18 Dec 2013 07:26:28 -0800 > Subject: Re: [Exchange] Quick straw poll: Email size limits > From: [email protected] > To: [email protected] > > 10mb external (send and receive), 20mb internal > > Kurt > > On Wed, Dec 18, 2013 at 1:26 AM, Nicholas Turner <[email protected]> wrote: > > We’re having the monthly battle with users about how big their attachments > > can be and I was wondering what you guys have set for the sending limits in > > your organisations. > > > > > > > > Out limits are currently set to 20mb internal and external (of course in > > real terms equating to about 15mb with mime encoding) > > > > > > > > I just want to send some info to users about current standards in sizing. I > > still consider 20mb to be quite generous myself! > > > > > > > > Nick > > > > > > This electronic message contains information from CACI International Inc or > > subsidiary companies, which may be confidential, proprietary, > > privileged or otherwise protected from disclosure. The information is > > intended to be used solely by the recipient(s) named above. If you are not > > an intended recipient, be aware that any review, disclosure, copying, > > distribution or use of this transmission or its contents is prohibited. If > > you have received this transmission in error, please notify us immediately > > at [email protected] > > Viruses: Although we have taken steps to ensure that this e-mail and > > attachments are free from any virus, we advise that in keeping with good > > computing practice the recipient should ensure they are actually virus free. > > > > CACI Limited. Registered in England & Wales. Registration No. 1649776. CACI > > House, Avonmore Road, London, W14 8TS. > >
