Cannot send large email attachment on Snow Leopard Mail

Does it display any errors? if yes What error does it show? Does it happen with one contact or all?
This is most likely a problem between your mail server and out going mail server
Meanwhile try:
1. Making sure that there are no large attachments attached to the email
2. Keeping the outbox emails unread or else most mail servers won't send read emails.
3. Make sure you can connect to the internet
4. If your using an app, there is something wrong with the app's settings or install files so uninstall and reinstall the app

Hope that helps

there are size limits from your mail provider. Try an FTP transfer or Dropbox.

Servers provide information for websites, hold Web pages, protect other computers from infection, provide authentication services and hold large numbers of files. Servers also connect email systems together. The average Web surfer encounters many servers in a day without realizing it. The mention of servers only arises when things go wrong. For example if the Hotmail Mail Server is inaccessible the user will receive an error message that the server cannot be found.

Client-Server In standard network communication all computers fall into one of two categories: clients and servers. Servers are bigger computers with large storage capacity and fast processing power. A server centralizes services that enable applications running on client computers to have access to more resources than their own computer could handle. The client is the local computer, the one the user accesses. The local computer, the client, contacts a remote computer, the server, with a request for a service. If the server is available, it responds with the requested service or resource. b> Hotmail Hotmail uses several types of servers. The screen the user accesses is actually an email client. It lists delivered email and enables users to write new emails. Originally, this program was always resident on the user's computer. Hotmail revolutionized the provision of email services by making this interface available on a website. The website itself is hosted on a Web server. The chain of clients and servers in a simple email transaction with email can soon become complicated. The user, on a home computer, is sitting at the client. The client program is the Web browser. The Web browser contacts a Web server to get and display the Hotmail page. b> Hotmail Servers b> Although the Hotmail page is resident on a server, it is a mail client and is also called a Mail User Agent, or MUA. It sends all outbound emails to a server called a Mail Submissions Agent, or MSA. The MSA sends the email to a server called a Mail Exchange, or MX, which then forwards it to another server called a Mail Delivery Agent, where the email sits until the user commands the mail client to go and find any new emails. b> Missing Server b> The server that Hotmail reports it was not able to find could be the Mail Submissions Agent, the Mail Exchange, or the Mail Delivery Agent. If the message arise during the sending of an email, the likelihood is that it is the Mail Submissions Agent that could not be contacted. If the error message occurs when Hotmail goes to find new received emails, it is likely to be the Mail Delivery Agent that could not be contacted. In either case, the user's connection is with the Web server and not either of these servers. There is little that the user can do to fix this problem other than try again later.

Because of the age of this question, save yourself ALOT of headaches and use Gmail:

When you use Microsoft Outlook Express to send and receive mail to a Post Office Protocol 3 (POP3) or Internet Message Access Protocol (IMAP) server running Exchange 2000 Server or Exchange Server 2003, you may receive the following error message. Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity.

Hi

A free Yahoo Mail users have email attachment limit of 10MB, while paid Yahoo Mail Plus users have double email attachment limit of 20MB.

OS X mail can be quite sluggish at times. I know it sounds stupid, but have you tried just leaving it for a while? What does the activity monitor/loading bar in the bottom left show?
I have never had problems with this, but if I did, I would use a service like Dropbox or YouSendIt to share such large files.
Hope that helped!

the external domains must be blocked at the exchange server you can use web mail to send the mail

Ok, email can be setup using a bunch of different protocols. The difference is how directly you phones data and the data on the server interact. POP and IMAP are methods for receiving email from the server, to send they use a protocol called SMTP. With POP3, email is all downloaded to your phone and saved there, with IMAP you only download the headers (...a header is like the back cover of a book). An Exchange server can do SMTP with either POP or IMAP, but when it says configure for Exchange - it means actually connecting to the mail server and integrating contacts, calendar items, email, like the Outlook client on your Windows machine. This is obviously much more server intensive and requires special permissions to do.

POP and IMAP will require the following information to work. Your login name, your password, your server, and whether the connection is secure. To find these out you can go to your coporate webmail. The user name is what you put in the user login spot, as is the password, the server will usually be either mail followed by a dot and the second half of your email address, or the web URL for the mail server...if the web access page address starts "https" then the connection is most likely secure.

This link may help further...

if you are configuring outlook to a mail server , you should ask administrator what Max attachment limit is. usually there has to be a limit on sending attachments and it differs from mail service provider to other