I have Mac Mail 9.3 and it isn't receiving .mp3 email attachments, but I do receive regular emails without attachments on Mac Mail from my phone provider. These sound files are phone messages that my phone provider sends to me as an email attachment whenever someone leaves me a phone message. However, in a test I was able to send myself an email with an .mp3 phone message as attached to my Gmail account. Also, the .mp3 phone attachments appear on the website of my email provider. As such, the problem may be with Mac Mail itself. I have turned off my anti-virus program so that shouldn't be the cause. Thanks for any tips on how to troubleshoot the problem of not receiving .mp3 email attachments on Mac Mail 9.3 from my phone provider.