On a new project with a new client, I asked the mail server admins to set up an orgwide email address with me and a few others as members:

sandbox-no-reply@foo.com

Once you set up an orgwide email address, SFDC sends a verification request to ensure you are authorized to use this email.

But – no verification message was received; not to me, not to any of the email group’s members.

• Email deliverability in sandbox was ‘System’. A verification message should qualify as a system message
• Email deliverability tests worked fine across all IP ranges
• I could happily receive other SFDC messages such as security token requests

The solution …

• Client’s email system was Google Apps for Work.
• The email group did not allow by default email from outside the domain of foo.com
• Changing the group setting to ‘Public’ was step 1 of the solution and maybe the only step you will need.
• As I was doing sysad via my company, my email address was in cropredy.com, not foo.com. A further change was needed in the Group definition to make my email address an ‘owner’. This allows mail to be distributed outside of the domain, in this case to @cropredy.com