原贴https://www.cnblogs.com/dreamer-fish/p/16876232.html
Exchange邮箱用户发邮件失败，提示“ Client does not have permissions to send as this sender”
Exchange用户发邮件提示“550 5.7.60 SMTP; Client does not have permissions to send as this sender”
处理方法：
get-mailbox username |get-adpermission |select user,extendedrights，查看该用户的 “NT Authority\Self”是否具有“Send-As”权限，如果没有，添加上后即可
Get-Mailbox username | Add-ADPermission -User 'NT Authority\Self' -ExtendedRights 'Send-as'
