I have my own domain name and I had some issues with the delivery time. So, I started looking at the mail header to see where my mail was stuck and why. That is not the issue.. While messing around the header file I noticed that the mail header not only contains the device used for the mail but the version of the operating system on my device. Here is the data:

X-Mailer: iPhone Mail (13B143)

13B143 is the code of iOS version 9.1.

Why on earth should anyone know the exact version of my OS? Is there a way to prevent that? Is there an other application more discrete?

  • In your case, iPhone Mail can be the client email application used for sending the email. See this for some pointer example-code.com/vb/X-Mailer.asp Commented Dec 6, 2015 at 9:04
  • Yes, the native iPhone Mail app is the one I use. Is there another one that I can configure to be more discreet?
    – teravice
    Commented Dec 6, 2015 at 9:11

1 Answer 1


I doubt that this can be done in the mail application itself. But since you own your own domain, you might run your own mail server and some allow you to change the mail headers. If you use postfix take a look at header_checks.

But note that mail clients leave more footprints than just X-Mailer. You can also distinguish clients by the other headers, structure of MIME boundaries and much more. It's more complex but possible.

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