We don’t just agree with email best practices and policies, we set them. At our Email Deliverability Summit II, five new industry standards were presented for discussion and adoption by the ISPs, spam filters, and email marketers and other email senders in attendance at the by-invitation-only event. These standards received unanimous support and adoption from those in attendance, with many attendees who had been involved in Email Deliverability Summit I* indicating that they had already adopted these standards. [*Interesting side note: It was during the promotion of Email Deliverability Summit I that our CEO Anne Mitchell coined the term “deliverability”; she says “I was sure that I would get pushback, that people would say “There’s no such word!”, but instead here we are, nearly 20 years later, and it’s a well-accepted term!”]

Please note that the below represents a quick overview of the standards, and that full discussion and explanation of the standards can be found at the relevant links.

It is also crucial to understand that in addition to the standards articulated below, that it is understood that not only is a minimum of opt-in with direct consent required, meaning that it is never acceptable to add an email address to an email list without prior consent, but that the gold standard of best practices requires confirmed opt-in (also known as ‘double opt-in’). A minimum of single opt-in with direct consent is required by law in many countries, including all of the EU, all of the UK, Canada, and China. In addition, in the United States it is required by the terms of service of every email service provider (ESP) and every inbox provider.

The standards developed at Deliverability Summit II, which Summit was developed and hosted by ISIPP, are:

I. Bounce Handling:

1. Bounce Handling Policy: senders should mark an address as “dead”,
meaning the sender should remove the address from the delivery list and
not attempt to deliver to the address until the sender has reason to
believe that delivery rejection would not occur, if the following two
conditions are both met:

A. Three (3) consecutive delivery rejections have occurred; AND

B. The time between the most recent consecutive delivery rejection and
the initial consecutive delivery rejection is greater than fifteen days.

A sender should have the capability to manage delivery rejections
differently between ISPs, whether based on previous agreements or
explicit requests from these ISPs.

2. Reply Coding Standards: receiving systems should comply with RFC
and DSN codes. RFC 821, DSN or RFC 1894 are relevant standards. For
example, ISPs can use RFC 550 5.7.1 “Go Away” to indicate that the ISP
is intentionally rejecting the delivery of an email that is thought to
be in violation of the list hygiene policies indicated herein.

Link to white paper presented at Email Deliverability Summit II

Link to PDF version of original PowerPoint presentation presented at Email Deliverability Summit II

II. Publication of Email Permissions Policies for Sending and Receiving of

Both receivers (ISPs and spam filtering companies) and senders (such as email
service providers, email campaign provders, and email service bureaus)
should publish clear, publicly accessible requirement as to what they
require for receipt and transmission of email, and sending of email,
respectively. These requirements should be applied consistently.


1. Establish, implement, and post requirements for acceptance and
delivery of e-mail (including first line contact information for
delivery issue reporting) clearly on website, and apply consistently.

2. Establish, implement and publish uniform processes for complaint
feedback loop clearly on website and apply consistently.



1. Establish, implement, and post a policy prohibiting the sending of
unsolicited commercial e-mail (spam) clearly on website and enforce the
policy consistently.

2. Implement automated system to process complaints, requests to
unsubscribe, and delivery failure notifications. Additionally, honor
all requests from recipients to modify permission preferences.

III. Unsubscribe Request Handling

1. List managers should endeavor to provide an unsubscribe process
which requires the fewest number of “clicks” possible. A “1-click”
unsubscribe process is the ideal; it is understood that in some minority
of instances, a 2-click process may be necessary for security reasons.
Subscribers should not have to go through the process of having to
provide a password or to surmount other obstacles to removing themselves
from mailings they no longer wish to receive.

2. An unsubscribe request should result in the subscriber being
immediately removed from the mailing list, and subscribers should not be
required to continue to receive, and should not continue to receive,
certain types of mailings from the sending site once they have submitted
their unsubscribe request. An exception to the latter is understood for
free sites which as part of their terms and conditions require
users to receive promotional mailings in exchange for free services
(see #3).

3. If the ongoing receipt of certain types of email is required in
order for a user to participate and continue to participate in a
program, this should be made very clear and explicit during the sign-up
process, and before the user concludes the sign-up process. In addition,
there should still be a clear and obvious way for the user to opt out of
the program.

IV. Multiple Addresses in Mailing List Mail

All mailing list mail should be sent “one address per piece”, meaning
that each piece should be addressed only to the primary recipient, and should not be cc:ed or bcc:ed to additional addresses. If there are 100 users on the list, 100 individual pieces
of email should be sent.

V. Communication Between Senders and Receivers

Senders and receivers should participate in an inter-industry
communications facilitation program to help ensure that they can
communicate effectively and in a timely manner when an email delivery
problem occurs. This can be ISIPP’s SuretyMail Email Accreditation program, or another such program.

Mailing List Hygiene Best Practices

As the email industry in general – and the email marketing industry in particular – has evolved, email mailing list hygiene best practices and expectations have evolved as well.

In addition to timely bounce handling, it is now expected that ESPs as well as other organizations who send out email marketing, newsletters, and other mass emailings, will monitor both open rates, and click-through rates (“CTR”), in order to identify email addresses that are dead, or have gone dormant, or which have otherwise demonstrated that they are not interested in engaging with the mailings, and will remove those email address from their mailing lists.

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