We are acting on the behalf of our customers and sending emails to their employees under certain circumstances. The customer would prefer that their employees think that the email messages were generated by an internal system.  For example,  they would like the e-mail message to appear that it came from PTO_Administrator@xyz.com   We have no problem sending out these e-mail messages, however, the concern is that messages from our domain will be marked as spam. Since we are acting on behalf of that customer  and the customer is happy to work with us to avoid having these e-mail messages marked as spam, is there anything we can do or the customer can do to avoid having these e-mail messages marked as spam?

I'm assuming you sent from outside of your customer's network anonymously and the email was marked as spam by your customer's mail hygiene gateway.

There are 2 ways to avoid it,

1. Obtains a valid user name and password from your customer and sent email with proper authentication
2. Configure the mail hygiene gateway to whitelist your email server so that it won't mark email from your server as spam.

• Proposed as answer by David Wang_Microsoft contingent staff, Moderator 4 hours 10 minutes ago

Have your customer add the list of IP/ranges for your email servers to their SPF record.

Hi,

I agree with vasil. Sender Policy Framework (SPF) is a method of fighting spam. As more time passes, this protocol will be used as one of the standard methods of fighting spam on the Internet. An SPF record is a TXT record that is part of a domain's DNS zone file. The TXT record specifies a list of authorized host names/IP addresses that mail can originate from for a given domain name. Once this entry is placed within the DNS zone, no further configuration is necessary to take advantage of servers that incorporate SPF checking into their anti-spam systems.

So please try to create an SPF record to test.

Regards,

David