I'm using php to send an html/text email with attachments. It works fine when the e-mail is sent to my main account, but when I send it to Gmail, the message is recieved, but it has no content or attachments. I've tried out a couple of different mailing scripts to test it out, and none of them seem to be able to send correctly to a Gmail account. However, when I send it to a different account using Thunderbird, I can view it just fine.

I've gone through the message with a fine-toothed comb to make sure it's formed properly, and it looks fine to me.

Any ideas?