Problem solve Get help with specific problems with your technologies, process and projects.

Why does an email's size increase when sent externally?

Learn what is causing an increase in message size when an email with an attachment is sent by an Outlook MAPI client from an Exchange 2003 server to an external Internet address.

What causes the 30% increase in message size when an email with an attachment is sent by a Microsoft Outlook MAPI client (from an Exchange 2003 server) to an external Internet address? Are there any guidelines to estimate the size increase various document types will experience, (i.e., .pdf, .doc, .xls, .ppt, etc.)?
I'm pretty sure that MIME encoding accounts for the message size difference you are seeing.

Do you have comments on this Ask the Expert Q&A? Let us know.

Related information from SearchExchange.com:

  • Tip: Outbound message size changes due to format conversions
  • Tip: How to set size limits for all local email messages
  • Reference Center: Exchange and Outlook mailbox management
  • Dig Deeper on Exchange Server setup and troubleshooting

    Have a question for an expert?

    Please add a title for your question

    Get answers from a TechTarget expert on whatever's puzzling you.

    You will be able to add details on the next page.

    Start the conversation

    Send me notifications when other members comment.

    Please create a username to comment.