All CLA requirements met.

@SteveL-MSFT Public API need approval by PowerShell Committee .

@replicaJunction Thanks for your contribution!

Please add tests (see Send-MailMessage.Tests.ps1 file).

@iSazonov I may need help adding tests for this. I did test interactively, and the reply-to field was correctly populated in an e-mail message, but even the existing Pester tests won't run on my development box since they're hard-coded to run only on Linux.

If I'm reading correctly, it looks like the existing tests actually call a mail server running on the local machine to send a message, and then they read the message back from disk. Could someone with easy access to a Linux device help with Pester tests?

@replicaJunction You could create new test like existing in Send-MailMessage.Tests.ps1 and push the commit - then you'll see result in CI (click Detail link).

I've added the -ReplyTo parameter to the existing tests, and it looks like they passed.

Regarding the CodeFactor issue above, I wrote the line in question to match the style of the existing code in that switch block. I don't think that issue can be fixed without reformatting the entire block, and I didn't want to clutter up this PR with formatting changes to others' code.

@SteveL-MSFT FYI. Waiting for PowerShell Committee to review this simple new public API.

@PowerShell/powershell-committee reviewed this. It should be understood that cmdlets are not considered APIs, so adding a new parameter that is implemented as a public member does not require @PowerShell/powershell-committee review unless the reviewers of the PR believe it is controversial or can not come to a consensus. In this case, -ReplyTo makes sense.

Exception for the CodeFactor issue seems reasonable. Merging,..

@replicaJunction Thanks for your contribution!