PDFs are downloading via imap with the wrong file size and are considered "corrupted"

Hello, I have a computer that is using thunderbird for imap emails. Any time I try to view a pdf attachment, the attachment wont open and is reported as corrupted. I downloaded a pdf directly from godaddy (email host) and I can view the file fine. I also noticed that the file i tested was 105K when shown on the godaddy webmail but was only 103K when listed as an attachment in thunderbird. I also forwarded the email to myself from the webmail and when I open the forwareded email, the file size is correct and the pdf now opens. I would like to be able to open the pdfs through thunderbird without having to forward them to myself from the webmail. Is there any settings i could change so that the pdfs will be correct the first time? Thank you