I created a google-group mygroup and asked to also create an email address for the group, mygroup@googlegroups.com. I want to email from my gmail account such that the sender address will be mygroup@googlegroups.com.
I went to Settings -> Accounts and Import -> Send mail as: -> Add another email address, added mygroup@googlegroups.com, checked "Treat as an alias" and clicked Next, but got a red error message saying "Please enter a valid email address".
How can I add this sender address?