Today we changed the maximum allowed email message size from 10MB to 20MB, for both incoming and outgoing messages.
In Web Mail you'll see the limit labeled on the Write Message view.
So now you can both send and receive files up to 20MB with an email message. Note that this is the combined size for all files you attach to the same email message.
This is a good time to explain why sometimes the size of an email message is not exactly what it seems and can be confusing. Our limit of 20MB is a true limit meaning you can actually attach a file to your message that is right at 20MB (allowing a few extra bytes for the message body) and send it. And you can receive that same file. But when you look at the received message in Web Mail (or your Sent copy) you may notice in the Size column that the message is now about 27MB. That's because all files attached to any email must go through something called MIME encoding for transport. That makes the files bigger, usually about 35% bigger. And it's stored in your mailbox in the encoded form until you retrieve the file and save it to your computer, at which point your email program (or Web Mail) decodes it for you and restores the original size.
So we actually allow you to receive messages that are 28MB after encoding, because a 20MB message will get about that big when sent. And you can send out a 20MB file either from Web Mail or from your favorite email program, and we allow for the extra size from encoding on the back end.