I have looked around the internet, I didn't find other ways than to read a txt file into the clipboard and to create a new message with the contents. Is this the way you meant?
But, then I still need the read commando...
How long is the text you want to email? You said earlier that it was too long, but you never said how long that was.
Details are important.
Have you looked at Automator? It has many mail commands. "New Mail Message" will take a text as input and create a new mail with the text as the email's contents.
One way to convert a filename input into its text contents is a Run Shell Script command that contains this:
The "pass input" popup should be set to "as arguments".
EDIT:
Suppose I, chown33, wanted to replicate what you're seeing. So I want to see the error in AppleScript, see the too-big file, and so on. In short, I want to try doing this on my machines.
The problem is, I can't try it. You haven't provided enough information.
My earlier reply was one example. I tried what you posted. It worked. It didn't fail like yours did. Since mine worked, then at that time, I didn't know why yours was failing. I thought of several possible reasons.
I briefly posted my results, and gave details (size of file, etc.). You then confirmed the problem was file size, but you didn't post what size caused the problem.
If the file is too big for AppleScript's
read command, but you absolutely must send it in the contents of an email (rather than an attachment), then we need to know what size that is. No one can try making a solution without that information. The file's size is one of the requirements.