I think you mean MegaBytes because 1.5 megabits is roughly only 190 KiloBytes and if this is the case then get a different e-mail account.
Apart from compression which has been mentioned, you could upload your file via ftp to a free website account such as geocities and then send the link in your e-mail rather than the file.
Your recipients will still be able to access your file and they don't have to download a large message if they don't use web based mail.