After upgrading to High Sierra (I think) I've started receiving the following message almost every time I start up Terminal:

    You have new mail in /var/mail/MyUsername

I had some [problems][1] upgrading to High Sierra so I strongly suspect this started after the upgrade, but cannot be absolutely certain.

When I enter the `$ mail` command and read the messages (which can amount to hundreds at one go) this is what is written:

    Message 1:
    From [email protected]  Tue Nov 28 21:37:04 2017
    X-Original-To: MyUsername
    Delivered-To: [email protected]
    From: [email protected] (Cron Daemon)
    To: [email protected]
    Subject: Cron <MyUsername@Users-MacBook-Pro> /Users/MyUsername/Library/symmetrical.xm/symmetrical.xm cr
    X-Cron-Env: <SHELL=/bin/sh>
    X-Cron-Env: <PATH=/usr/bin:/bin>
    X-Cron-Env: <LOGNAME=MyUsername>
    X-Cron-Env: <USER=MyUsername>
    X-Cron-Env: <HOME=/Users/MyUsername>
    Date: Tue, 28 Nov 2017 21:37:01 +0800 (+08)
    
    /bin/sh: /Users/MyUsername/Library/symmetrical.xm/symmetrical.xm: No such file or directory

Also, when I use `$ crontab -e`, this is what is shown:

    37 * * * * /Users/MyUsername/Library/symmetrical.xm/symmetrical.xm cr
    ~                                                                                                                              
    ~                                                                                                                             
    "/tmp/crontab.SsevmMDt1o" 1L, 72C

I'd really appreciate it if someone could help me understand how this started and what I can do to stop it from happening (or if I should stop it from happening at all). I've read somewhere that deleting the `MyUsername` file at `/var/mail/` would stop these emails from coming in but I really want to know why the Cron Daemon is sending me these error messages in the first place.

Thank you!

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macOS High Sierra v10.13.1 (17B48)

  [1]: https://forums.macrumors.com/threads/macos-could-not-be-installed-on-your-computer-fixed.2058800/#post-25149270