Sometimes, customer may create some email forwarder, which forwards emails from (e.g.) to or

Then, some other Internet user, e.g. may send email to .  In theory, this email shall be stored in and forwarded to .  However, in practical, this email may sometimes fail to deliver to

The reason is that may check whether the sender SMTP server (the IP) is the authorized SMTP server of the sender domain.  This checking is based on SPF (Sender Policy Framework, or called Sender Id)

For the above example, when our SMTP server forward the email from to . server will check this email.  The sender domain is , but our servers are not the authorized SMTP server.  So, Hotmail may have chance to reject this email, and raise the following error –

IP xxx.xx.xx.xx soft failed sender ID check. Please ensure this IP is authorized to sent

From the time being,, (and a few other large email service provider) may employ the above SPF to check the incoming email (to reduce spam)


This is the SMTP RFC design issue.  If you do want to receive email inside Yahoo/ , you may consider to use their webmail interface and import other POP3 account email into Yahoo/

For example –




For please refer to

For Office 365, please refer to


Pin It on Pinterest

Share This