The biggest thing to remember here is that sending FROM your linux.com vanity address probably won’t work well. Yes, you absolutely can set your “mail from:” address to anything you want, but without corresponding SPF or DKIM records in the linux.com DNS server (which you can’t control and they won’t do), most major email providers will either send your messages to spam or outright reject them.
The biggest thing to remember here is that sending FROM your linux.com vanity address probably won’t work well. Yes, you absolutely can set your “mail from:” address to anything you want, but without corresponding SPF or DKIM records in the linux.com DNS server (which you can’t control and they won’t do), most major email providers will either send your messages to spam or outright reject them.