Less audio file

I have now tried to make my first file in PODCAST. It worked fine, but I wonder you can not get the file smaller in one way or another as it would be too big to send by e-mail. I found out as exported mixdown as a wave file full of 5490 kb - and as mp3 filled 765 kb and as a wma file it filled it 535 kb. The audio file is 28.3 sec. Are there other options if I make a long podcast to sendt with email get it down in size? Thanks in advance!