I just asked to change the sender address of a massmailing to the address '{$mailing->fromemail}'.
Because this is not my own address the massmail system sends a verification message to the indicated email address and asks for approval.
If you can read this message you can answer this question and allow (or reject) the mailing to use this email address.
Do you want to approve or reject this change? If you do not perform any action the message cannot be sent out with this mailaddress.
Sincerely,
{$luser->name}
through the massmail application at {$cfg->base_url}/mailing/{$mailing->primary}.