BB Curve :: Cannot Receive Mails With Large Attachments

So I have BIS enabled for my BB Curve 8900 and an email account set up on it. The email works fine, I receive emails and I can send email messages from my BB. However, I noticed today that I do not receive emails on my BB that have attachments larger than 7 MB. I have the same email account set up in my Thunderbird client and everything works fine with it, I do get all these large emails. I contacted my service provider (Orange) and they could not figure this out.