E-mail "Overhead."

cwizardone · 09-15-2009, 08:55 PM

I created a 3.2 meg .pdf file, attached it to an e-mail, typed eight words, and when I looked at the message in the sent-mail box the software said the message was 4.7 megs in size! I know the header adds a bit, but 1.5 megs of text is enough for a book.
Where is that 1.5 megs coming from?!

Thanks.

docalton · 09-15-2009, 09:37 PM

The "overhead" you are referring to is the encoding process. In email, an attachment is first turned into a string of characters and then
that string of characters is added to the email.

There are several encoding methods including uuencode, mime, and binhex.

davidsrsb · 09-16-2009, 07:16 AM

Email transfer is not assumed to be 8 bit transparent. There were many systems that could only handle 7 bit (ascii) so your pdf file is converted to ascii characters. Typically every 3 bytes of data is converted to 4 ascii characters, hence the expansion that you see