Changing sender on Gmail / Outlook.com email:
To prevent spoofing - Gmail/Outlook.com won't let you send from an arbitrary user account name.
If you have a limited number of senders you can follow these instructions and then set the From
field to this address: Sending mail from a different address
If you are wanting to send from an arbitrary email address (such as a feedback form on website where the user enters their email and you don't want them emailing you directly) about the best you can do is this :
msg.ReplyToList.Add(new System.Net.Mail.MailAddress(email, friendlyName));
This would let you just hit 'reply' in your email account to reply to the fan of your band on a feedback page, but they wouldn't get your actual email which would likely lead to a tonne of spam.
If you're in a controlled environment this works great, but please note that I've seen some email clients send to the from address even when reply-to is specified (I don't know which).