The total allowed message size at EarthLink, including the message text and all attached files, is 10MB. This limit applies to both incoming and outgoing messages, and applies whether you use Web Mail or other email software.
A 10MB limit is used by most major email providers, so even if we allowed larger limits, many of your recipients wouldn't be able to receive the file. Email isn't really a suitable medium for moving around very large files, and was never intended for that use. If you need to give someone a large file, use one of the many free services that let you upload any size file and then email a link to your recipient to retrieve it. Or post the files on your own web site if you have one.
For techies: we also make an allowance for the MIME encoding bloat so that you can actually send or receive a 10MB file. Some services advertise a 10MB limit, but enforce it after MIME encoding, so that you can actually only send about 6.5 MB in attached files on those services. We allow a full 10MB plus a little margin. (MIME just refers to a set of encoding standards used to turn all email content into ASCII text for transport, and the email program on the other end knows how to un-encode it. ASCII basically refers to the set of characters you see on an English keyboard, plus a few others. That's why if you "View Message Source" for an email message with attachments, you see a big block of printable text for your attached files. That's encoded binary data.)