Email header MIME encoding

[#1]

Hi,
A friend of mine is sometimes having problems when forwarding emails with attachments. The recipients he is sending the emails to are receiving several copies of the same email.
He is running Windows Live Mail software on a Windows 7 platform.
I noticed that the offending received emails have the following metadata in the email header:
MIME-Version: 1.0
Content-Type: message/partial;
total=9;
id="01CF7B34.D6EC25F0@jim-PC";
number=2
From the above, total = 9 means that the recipient received the same email nine times. The above email was number 2 of 9.
I believe that this particular MIME encoding is not used any more due to the improved bandwidth of internet connections, so that sending data does not need to be broken down into several chunks and then reassembled at the other end. Nonetheless how is it possible that this encoding is still included in the header and how can he ensure that when forwarding emails with attachments to recipients that this problem doesn't re-occur. Suffice it to say my friend has a Plusnet email address.
I don't think this is the characteristics of malware or a virus. Nonetheless, I have run several antiviris/malware scanners over the hard drive, deleted all System Restore points, trashed everything in the Temporary folders, and checked installed programmes and MSCONFIg to see if there is anything suspicious. I couldn't find any indications of a virus/malware.
Many thanks,
Mark

[#2]

In Outlook Express (father of Windows (Live) Mail), there is an option in Advanced email account settings to "Break apart messages over:" (size - from memory I think it defaulted to 60KB). This option is not selected by default and may no longer exist, but it's worth a check (or in this case uncheck...).

[#3]

Hi,
I am much obliged for the lead. It was indeed checked to 'break apart messages' into 40 KB chunks. It has now been disabled and seems to be working fine.
Many thanks once again,
Mark

[#4]

Glad to hear it.