Why has Outlook Express split my email attachment into gobblegook?

Q I use Outlook Express to send photos to friends. Recently, though, I encountered a problem when sending such an email.

The application displayed a message saying the email was too large, followed by an offer to reduce the size of the message by splitting it up. I accepted this and the message seemed to send just fine.

However, my friend told me that all they received in their email inbox were lots of individual meaningless emails, rather than the photos I sent. This now seems to happen whenever I send any photos.

Also, I do not understand why the email was too large. My broadband internet service is supposed to be ‘unlimited’, so what’s going on here?
Alice Narlan

A For all manner of arcane reasons, many internet service providers (ISPs) place limits on the size of files that may be sent and received as email attachments.

These apply specific messages sent via the company’s own email servers. If your ISP applies such a limit – and almost all of them do – then the level of internet service you have is irrelevant: the email servers will reject any attempt to send (or receive) messages larger than the decreed size.

Attachment limits vary from ISP to ISP but five or 10MB is typical. Of course, by modern standards these are trifling amounts of data but, as we said, attachment limits owe their existence to a complex mix of historical, technical and the resistant attitudes of some ISPs.

Some companies are a little more enlightened - Gmail, for example, allows 25MB attachments - but the bottom line is that email remains an unreliable way to send large files such as digital photos and videos.

So that’s some background about what led to your current woes. But what happened to Outlook Express? And why did your friend receive lots of unreadable emails?

The answer is that in trying to send that last photo-bearing email, you must have broken your ISP’s attachment limit. This prompted Outlook Express to offer you the option of using a little-known feature that breaks up messages into chunks likely to be smaller than the attachment limit.

If the recipient happens to use Outlook Express and all chunks make it through intact - some ISPs will detect and block broken-apart email attachments - then the constituent parts will be resurrected into a single attachment-bearing message.

However, if the recipient uses a different email program, it’s likely that the chunks sent by Outlook Express will be unreadable (or at least, gobbledegook). Some email programs may be able to rebuild the original message but the ‘break apart’ feature is not commonly used.

The best bet, then, is to switch off the feature. To do this, first launch Outlook Express then choose Accounts from the Tools menu – this displays the Internet Accounts dialogue box. 

Select the Mail tab, click to highlight the relevant email account in the Account list and click the Properties button. In the second dialogue box, click the Advance tab and then click to remove the tick from the ‘Break apart messages larger than’ box. Click OK followed by Close.

If you want to send larger email attachments then consider using a webmail service (such as the aforementioned Gmail). Alternatively, try one of the numerous services that exist to send large files: the free version of Yousendit, for instance, will let you send files of up to 100MB.