For your own safety, servers are set to block several types of attachements, such as .bat, .src and .exe, that may cause secutity issues. In case you need to send a file of this type, you need to create a zip file and atttached the zipped file. Another reason your attachements are not received is their size, which should not exceed10MB, whether the email is sent via a mail client or webmail. There are though some type of files such as .gif, .jpg, .html., .pdf, and .doc. which can be send without having to be zipped first.
