Download of MailSpy 1.0.5 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. The program belongs to Communication Tools. The actual developer of this free software for Mac is Albert Mayer.
From the developer:
MailSpy is an application that can show you the geographic location from where the e-mails you've received have been sent. MailSpy shows the sender location as well as the location of any intermediate 'stops' the e-mail may have taken on its way to you, as well as additional information, like the e-mail client the sender has used.
You may want to check out more software for Mac, such as MailStewardLite, Serial Mail or AdvancedMacMailer, which might be related to MailSpy.