Recommendations: sending email on behalf of users

Question

The company I work for provides testing services for the healthcare industry. As part of our services, we need to send an email to our clients' employees. As a rule, these are temporary, part-time or contract employees, therefore they have personal email addresses (for example, Hotmail, GMail, Yahoo !, etc.).

So far, we have sent from the internal address, but this means that the answers come back to us when employees do not pay attention or do not know to send requests to our customers. I would like to change this, so the person who asks to send an email is the one that was answered.

We used the answer for: in the past, but it seemed to cause additional mail to be delayed by spam filters.

I read about the sender: and on behalf of: the headers, and wondered what was the best practice for sending email in a scenario where we need to send an email so that the response goes to the domain we do not control.

Answer 1

The on-behalf-of header is the best way to do this, but you will also fall into the trap of spam filters. The best way to mitigate or reduce the likelihood that you will get into a spam filter is to implement all industry standards related to checking your domain and mail server. As stated in this article:

http://www.codinghorror.com/blog/2010/04/so-youd-like-to-send-some-email-through-code.html

However, this is very difficult to do, because you need to stay on top of SPAM standards and comply with the laws of CAN-SPAM and everything else. It’s better to use an on-demand SMTP server with clouds like this:

https://www.postmarkapp.com

Use a company that is a domain expert in the field of sending email and has gone through all the work with your feet to get the maximum delivery speed. And it will remain at the highest standards for you and control blacklists for problems.

Answer 2

You are probably looking for Reply-To . This is an official and widely supported title, unlike On-Behalf-Of , and it does not undergo the same spam checks as From .

If you really wanted to act as a sending on behalf of another user, the “mainly” correct way according to SMTP standards would be to put your “real” address in Sender: and your client address (from which you, sending on behalf of) in From: However, From: specifically targets DMARC, a very strict anti-spam protocol implemented by most major email providers. They will not ignore the From: DMARC failure just because you have a valid Sender: header.

DMARC allows domain owners to specify how SPF and DKIM should be applied to the From: header. A popular policy is to reject email that fails with either SPF or DKIM, which means your email address will not even be marked as spam: it will be rejected.

Sender: + From: still works technically. It was originally created with the goal of being used by people in one organization, such as a secretary or assistant. This has become a difficult limitation with the advent of spam prevention mechanisms.