PDF attachment size bloats when sent

[Dave Schroeder]

I have users that have difficulty sending large pdf files
to an external address. An email will be 4MB in total size
(including the pdf attachment)...

The following message is returned by the mail server:
"The content length of the message is too long for the
recipient to take delivery".... when looking through the
logs on Exchange 5.5, it appears that the size has been
bloated by around 1.5x original size. This only happens to
PDF file attachments.

There is a limit of 5500k for sending to external
contacts, as this is the limit also imposed by the ISP.

Can anybody tell me why this happens to PDF attachments,
and if there is a work around?

The users are using: Outlook XP, with Exchange 5.5

 

[Brian Tillman]

I have users that have difficulty sending large pdf files
to an external address. An email will be 4MB in total size
(including the pdf attachment)...

The following message is returned by the mail server:
"The content length of the message is too long for the
recipient to take delivery".... when looking through the
logs on Exchange 5.5, it appears that the size has been
bloated by around 1.5x original size. This only happens to
PDF file attachments.

Email systems cannot transmit binary data, only ASCII text. Thus, in order
to trasmit a binary attachment, like a PDF file, the attachment must be
encoded, converting the binary data into text characters (with the reverse
happening on the receiving end). Text cannot represent quite as much
information so the attachments generally expand in size by a certain
fraction. In your case, that fraction is 50%. And it doesnt' happen only
with PDF attachments. ALL binary attachments generally expand by some
amount when being encoded.

Can anybody tell me why this happens to PDF attachments,
and if there is a work around?

It's doubtful that zipping or otherwise compressing the attachment will make
much, if any, difference because binary files are generally not
compressable, but try zipping the PDF prior to see if its size will
decrease. If that doesn't work, the only choice you have, if your ISP won't
increase the limit (and for a business customer, I can imagine they would),
then you'll have to break the document into smaller pieces prior to sending.