This document provides best practices for email deliverability across 15 areas, including reputation, segregation, bounce management, permission, frequency, relevance, branding, CAN-SPAM compliance, suppression lists, policy requirements, and technical requirements like authentication and DMARC. Following these practices can help boost deliverability rates and ensure emails reach customers, while avoiding issues that could damage sender reputation or cause blacklisting.

1. Email Best Practices 101
15 Proven Tactics for Boosting Deliverability and Engagement
BY KATE NOWROUZI

2. 2
Email Best Practices 101
Boosting your inbox rates begins with an understanding of how your tactics in
several key areas can affect deliverability. Read on to learn how to improve the
ROI of your email operations by applying best practices for:
The Dollars and Cents of Deliverability............................ 3
What’s at Stake ..................................................................... 4
Reputation.............................................................................. 5
Segregation............................................................................ 6
Bounce Management........................................................... 6
Permission.............................................................................. 7
Frequency............................................................................. 10
Relevance.............................................................................. 11
Branding ...............................................................................12
CAN-SPAM.............................................................................13
Suppression Lists................................................................ 14
Policy Requirements.......................................................... 14
Technical Requirements......................................................15
IP/Domain Acquisition • Valid Reverse DNS • Role Accounts
Authentication • How DMARC Works • Whitelisting
Sender Score Certified • Spamhaus • Feedback Loops
Email Delivery Platforms................................................... 23
Adaptive Email Network...................................................24
Conclusion ........................................................................... 25

3. 3
The Dollars and Cents of Deliverability
According to an April 2015 survey of U.S. marketing executives,
email alone accounted for as much in revenues as all other
types of digital advertising combined–including social media,
website, and display ad efforts. And other surveys repeatedly
have found that email has a higher ROI than any other channel
or format studied.*
Done correctly, high-volume email operations can deliver
tremendous return on investment. But email only works if it
actually reaches your customers. Most businesses achieve a
deliverability rate somewhere around 87%. In other words,
about 13% of their messages fail to reach their recipient.
That’s simply not acceptable.
Whether your focus is email marketing, onboarding and user
engagement, or customer service, every undelivered message
is a missed opportunity — and a hit to your bottom line. Don’t
let mediocre deliverability rates erode the value of your email
operations. The best practices discussed in this e-book will
help you ensure the best possible inbox rates — and the ROI
your business deserves.
* See “How Much Revenue Does Email Drive?,” eMarketer, http://www.emarketer.com/Article/How-Much-Revenue-Email-Drive/1013001
and “Direct Mail Gets Most Response, But Email Has Highest ROI: DMA,” ChiefMarketer, http://www.chiefmarketer.com/
direct-mail-gets-most-response-but-email-has-highest-roi-dma/
$7.30
$19.72
$10.51
$22.24
$40.56
ROI on email marketing
is nearly double that of
other programs.

4. 4
What’s at Stake
You can’t afford to be complacent about middling deliverability rates. Even rates that might seem
“good enough” still translate into lost revenue. Consider two examples based on typical industry
metrics. Can you really afford to lose $100,000 for every million messages you send?
BUSINESS A: 95% Deliverability Rate
Subscribers: 1,000,000
Delivered Messages: 950,000
Missed Messages: 50,000
Average Sales: 5%
Lost Sales: 2,500
Avg. Value Per Sale: $20
Lost Revenue:
$50,000
BUSINESS B: 90% Deliverability Rate
Subscribers: 1,000,000
Delivered Messages: 900,000
Missed Messages: 100,000
Average Sales: 5%
Lost Sales: 5,000
Avg. Value Per Sale: $20
Lost Revenue:
$100,000

5. 5
Sender reputation is one of the most important
concepts in deliverability. Every IP address and domain
has a reputation based on factors such as past rates of
bounces and spam reports. Domains and IP addresses
with a good reputation have a better delivery rate —
so building and maintaining a good reputation should
be central to the mission of your email operations.
Reputation
A Few Tips to Begin With:
Avoid sending risky content, especially on new
IP addresses with unproven reputations.
Don’t use language that could seem suggestive
(“sexy,”“hot”) — even if your meaning is entirely innocent.
Don’t send too much, too soon, from a new IP address.
Start slowly and increase gradually.
Maintain good list hygiene. Respect user permissions,
pay ­attention to feedback loops (FBLs), and remove ­
inactive users.
Authenticate. Use DMARC, SPF, and DKIM.
Segment and mail your active subscribers to build
a ­positive track record.
Monitor the inbox rates of your IPs to identify
emerging problems.
Watch out for deferral messages from your ISP, which
can ­indicate impending blacklisting of your emails.
Most fundamentally, make sure each email you
send will be welcomed by its recipient — instead
of being reported as spam.

6. 6
Each message that bounces or gets reported as spam counts
against the reputation of the originating IP. This reduces deliv-
erability for future messages from that IP — or leads to them
being blocked entirely.
Using the same IP for every type of email — user, marketing,
transactional, alerts — means that a rogue email in any of
these areas can jeopardize the deliverability of every message
your company sends from that IP.
By segregating your IPs according to function, you help
ensure that your mail receives the best delivery possible.
A high bounce rate can have a negative impact on your
overall delivery rate. If your IP address is associated with too
many “unknown user” bounces at a particular ISP, you risk
being blacklisted or blocked by that ISP.
Each bounce has a unique meaning and needs to be
treated differently based on its associated SMTP code.
The art of classifying and treating bounces is called
bounce management.
Segregation Bounce Management

7. 7
Permission is the consent consumers grant to receive emails from you. It’s important because
email is so much more personal than TV, radio, direct mail and other marketing channels, and calls
for a higher standard of privacy. It’s also an area of intense attention by government regulators in the
U.S. and around the world. Most importantly, permission affects deliverability. An AOL User Behavior
study showed that email newsletters using “double opt-in” had a much lower average unsubscribe
rate (7.6%) than “single opt-in” messages (22.2%). There are two main forms of permission:
Permission
SingleOpt-In:
The user enters an email address in a web form and checks a box agreeing
to receive marketing emails, alerts, and other messages from the business.
DoubleOpt-In(a.k.a.closed-loopopt-in)
The recipient needs to actively respond to a confirmation email sent after
the form is filled out, either through a click in the email or by responding
to the message itself.

8. 8
While permission is a key issue for email marketing,
it may be less relevant for other types of commercial
email — for example:
Current balance alerts sent to a bank’s
account-holders.
Activity notifications sent by social networks
or online services.
Flight updates sent by an airline to ticket-holders.
New listings sent to members of a job search site.
In cases like these, a user’s messaging preferences are often
set by default to receive email. Instead of triggering the spam
reports and damaged IP reputations that unwanted marketing
emails can bring, though, the context and relevance of these
emails are more likely to provide welcome value for the recipient.
Let your customers be your guide. Your engagement metrics
(both positive and negative) will tell you whether they truly find
your content relevant to their needs and whether your practices
are aligned with their preferences. Handled carefully, prefer-
ence-aware messaging can be a win-win for your business, your
customers and your deliverability rates alike.
Beyond Permission: Really Listen to Your Customers
[ Permission ]

9. 9
MonitorMetrics
Such as opens, click throughs, and changes in communication preference settings to make sure
you’re giving customers what they really want.
IncreaseMessagingIntelligence
Implement customer-adaptive messaging capabilities to fine-tune your emails by variables such
as timing and frequency according to your customers’ preferences and other factors.
MakeEmailsWorthReceiving
Work to optimize your messages by every means possible, including more relevant content,
subject lines and targeting.
KeepDataClean
Send a confirmation or welcome email to make sure that addresses are deliverable and you’ve
correctly captured customer preferences before repeatedly mailing them. Purge unknown users
and non-responsive addresses.
GetPermissionAnyway
Even if you know your customers will welcome your messages, you should make sure to capture
their complete preference profile (including what they prefer you not do, such as data sharing)
and act on them in every action you take.
Guidelines for Preference-Aware Messaging
[ Permission ]

10. 10
Frequency
It’s important to ask your customers, through the sign up
process or a preferences center, how often they want to receive
emails from you. While respecting their wishes, you should
also be aware of the right frequency strategies for different
types of emails.
Marketing emails are typically looking for an action —
a click, a purchase, a registration for a new service. Higher
frequency can increase these conversions, but after a point
customers may feel harassed or start tuning them out. Start
slowly and monitor unsubscribe rates closely as you increase
frequency. The last thing you want to do is damage your list
through overuse.
Engagement emails such as newsletters should be sent at
regular intervals so customers know when to expect them.
Again, sending them too often can cause burnout — quality
is more important than quantity.
For account alerts, activity notifications, and other customer
service messages, let customers set their own preference for
real-time, daily, weekly, or other messaging schedules.
You should also pay attention to the aggregate frequency of
all the emails of any type each customer receives to ensure that
your brand isn’t showing up in their inbox more often than they
might want it to.

11. 11
The more relevant your emails are, the more likely they’ll
be welcomed by consumers. Of course, relevance is in the
eye of the recipient — but a few guidelines can help you
hit the sweet spot.
Target the Right Audience. Use past purchases, traffic logs, on-site
search, and other data to learn what your customers are most inter-
ested in, and tailor their content and offers accordingly.
Don’t Be Too Broad. While some messages may be relevant for
your entire list, most won’t be. Avoid the temptation to blanket the
world with a single email in the name of efficiency; sending multiple
waves of more targeted messages will be much more effective —
and better for your list and your reputation.
Send Valuable Promotions. Who doesn’t love a good offer? Don’t
just tell customers about your latest products; make it worth their
while with a significant discount or package deal.
Use a Good Subject Line. Remember that many customers won’t
see more than the first few words — especially on mobile. Put the
most relevant and targeted terms up-front, and make the value to
the customer immediately clear.
Relevance

12. 12
Branding is one of the most important elements of
email marketing, helping you shape the way customers
view your products and your company.
To ensure brand integrity, it’s essential that every aspect of
your messaging — visual identity, voice, value proposition —
is consistent and compelling.
A common pitfall is to use different systems or third-party
providers for automated transactional emails, marketing emails,
and other types of messages. This can lead the look and feel
of the messages customers receive to vary widely, creating a
confusing brand experience.
By managing all messages through a single system, you
can build a stronger connection with your customers and
make each email they receive feel part of a coherent and
valuable relationship.
As part of your branding strategy, it’s a good idea to use your
brand name in the “from” field that shows up in the recipient’s
inbox. Some marketers use an individual’s name in the belief
that it will seem more personal, but this can also make it seem
like spam. Instead, use a name customers will expect to see,
then stick with it consistently across all emails to build
recognition and trust.
Branding

13. 13
Also known as the Controlling the Assault of
Non-Solicited Pornography And Marketing Act of 2003,
CAN-SPAM is an attempt by the U.S. Congress to protect
consumers from unwanted marketing emails. While enforce-
ment of the law is difficult and its effectiveness has been
debated, its provisions offer useful guidance for treating
consumers appropriately and maintaining a healthy
online reputation.
CAN-SPAM
Key provisions of CAN-SPAM include:
Don’t use false or misleading header information.
Don’t use deceptive subject lines. Identify the
message as an ad.
Tell recipients where you’re located.
Tell recipients how to opt out of receiving
future email from you.
Honor opt-out requests promptly.
Monitor what others are doing on your behalf.

14. 14
Suppression Lists
The CAN-SPAM Act requires commercial email senders to
maintain a list of consumers who do not wish to receive their
emails. These businesses must provide a functioning opt-out
mechanism by which email recipients can unsubscribe their
email address from future email messages. The unsubscribed
email addresses are placed into a suppression list that is used
to “suppress” future messages to that address. This list also
includes bad domains, traps and role accounts.
ISPs accept email from senders at different rates. Before
you start sending email from a new IP, make sure you
comply with as many published ISP acceptance policies
and recommendations as possible.
Policy Requirements

15. 15
Technical Requirements
In addition to the best practices above, there are several technical
­capabilities that can play a crucial role in deliverability. These include:
Sender Score
Certified
WhitelistingAuthentication
(DKIM, SPF, SenderID)
Valid Reverse DNS for
All Sending IPs
IP/Domain
Acquisition
Role Accounts
(postmaster@ and abuse@)
Feedback Loops
(FBL)

16. 16
Most businesses that send commercial email
will want to set up multiple web domains
and IP addresses for different purposes —
sometimes over 100 for the largest senders.
Acquiring these is a simple matter; you can begin at the
following sites:
IP Addresses:
arin.net
The American Registry for Internet Numbers
Domain Name Registration Provider:
networksolutions.com
Godaddy.com
It takes about 24 – 72 hours to propagate a new domain name.
As you acquire new IP addresses, you should be aware of the
concept of IP warm-up. To combat spammers, ISPs and email
providers temporarily block or limit the amount of email a new
IP address can send, allowing higher volume only gradually as
the sender’s reputation is proven. If you try to send millions of
messages on your first day with a new IP address, you’ll quickly
be blacklisted.
Becoming a high volume sender (millions per day to the big
ISPs) is possible, but it takes time. One recommendation is to
avoid sending more than 10,000 messages per day to the major
ISPs (Yahoo!, Gmail, Hotmail, AOL, etc.), or more than 1,000
messages per day to smaller ISPs, and don’t increase volume
by more than 2x per day. Watch your failure metrics carefully,
and revert to a lower volume if you start seeing an increase in
temporary and permanent failures.
IP/ Domain Acquisition
[ Technical Requirements ]

17. 17
Computer networks use the Domain Name System (DNS)
to determine the IP address associated with a domain
name — for example, resolving host1.domain.com to
192.1.2.4. Reverse DNS Lookup works similarly, but
in the opposite direction, resolving an IP address to its
­designated domain name — so the IP address 192.1.2.4
turns back into host1.domain.com.
To ensure the integrity and operability of DNS data and
servers, every Internet host is required to have a reverse
DNS entry. In practical terms, mail servers with no reverse
DNS will have a hard time getting mail to certain large ISPs.
Valid Reverse DNS Role Accounts
A role account is an email address which serves
a particular function, not an individual person,
for example abuse@, sales@, or info@.
Every ISP, email service provider (ESP), and web host —
including self-hosted senders of commercial email — is
required to have two particular role accounts in order to
promptly identify spam and abuse related problems on their
network: postmaster@domain and abuse@domain.
Networks that do not tolerate spammers monitor their
abuse@ email closely and take prompt action to stop any
problems that arise.
[ Technical Requirements ]
SPAM

18. 18
Email authentication validates the identities of the parties
who participate in transferring a message — the sender and/or
recipient — and can be an important factor in deliverability.
Early authentication schemes, such as DomainKeys, have
been superseded in recent years, and today the industry has
coalesced around DMARC as the standard protocol.
DMARC
Domain-based Message Authentication, Reporting and
Conformance, is designed to guard against phishing, spam
and other email abuses. When a message is delivered to a
recipient, the destination server asks the sender for a public
key to verify that the signature is correct and that the sender
is who they claim to be. What’s important for commercial
email senders to know is that if their email is not DMARC-
compliant, their deliverability can suffer significantly. Adopting
DMARC is quickly becoming an essential requirement for
high-volume email operations.
Authentication
[ Technical Requirements ]

19. 19
The DMARC standard allows senders to employ either of
two (or both) previously established authentication standards:
SPF (Sender Policy Framework, a.k.a. SenderID) and DKIM
(DomainKeys Identified Mail). The critical mechanism with
DMARC is that it creates a dialog between senders and receivers,
with senders providing guidance to receivers as to what to do if
neither of the authentication methods passes. For instance, if a
message fails DKIM, please junk or reject the message immedi-
ately. Additionally, DMARC provides a way for the email receiver
to report back to the sender about messages that pass and/or
fail DMARC evaluation.
SPF / SenderID
With SPF, records are used to authorize the IP address of
the outbound mail transfer agent (MTA) to help ISPs detect
forged email. Creating your SPF record involves determining
the domains and IP addresses used to send your emails, then
publishing the SPF to DNS.
DKIM / DomainKeys Identified Mail
DKIM authentication allows the recipient of a message to
confirm that a message originated with the sender’s domain and
that the message content has not been forged. In effect, DKIM
allows organizations to claim responsibility for messages they
send and guarantee their contents.
How DMARC Works
[ Technical Requirements ]

20. 20
Senders and consumers alike want permission-based email to
reach the inbox. To help separate responsible senders from
spammers, many ISPs maintain a whitelist of approved domains
or IP addresses. A whitelist will protect good senders from
some (but not all) spam filters based on previous reputation and
mailing history.
Being whitelisted by ISPs is a key step for increasing your email
delivery rates. Whitelisting lets you send more email per hour,
keeps you out of the spam folders, and gets more email deliv-
ered. It also increases your email reputation score.
Major ISPs such as AOL, Yahoo, Hotmail, and Verizon provide
whitelisting as a free service. To be whitelisted, you provide
the ISP with information about your mailing practices — which
also has the effect of making it easier for them to identify email
coming from you so they can monitor how recipients treat
your email. This higher level of scrutiny is the price you pay
for higher deliverability and a better reputation, but as long
as you’re diligent in following email best practices, you’ll have
nothing to worry about.
Whitelisting
[ Technical Requirements ]

21. 21
Sender Score Certified is a certification program for
enhanced inbox placement run by a company called Return
Path. Like a credit rating score, a Sender Score indicates the
trustworthiness of an email source, and is a key reflection
of your reputation.
A Sender Score is compiled based on data from ISPs, spam
filters, and security companies. It can help you determine
if you need to improve your reputation to improve deliver-
ability, and can provide specific guidance in the changes
you would need to make.
Return Path lets email senders check their Sender Score free
based on their IP address, and provides its customers with
more detailed reputation reports.
The Spamhaus Project is an international nonprofit orga-
nization whose mission is to track the Internet’s spam
operations and sources, to provide dependable real-time
anti-spam protection for Internet networks and to identify
and pursue spam gangs worldwide.
Spamhaus maintains a number of real-time spam-
blocking databases (‘DNSBLs’) responsible for keeping
back the vast majority of spam sent out on the Internet.
These include the Spamhaus Block List (SBL), the Exploits
Block List (XBL), the Policy Block List (PBL) and the
Domain Block List (DBL). These tools are highly valuable
for senders in maintaining good relations with ISPs, which
are on the “receiving” side of the email world.
Sender Score Certified Spamhaus
[ Technical Requirements ]

22. 22
When an email recipient clicks “This is spam” for a piece of
email, this is considered a “complaint.” If your complaint rates
are too high, an ISP may not deliver your email.
By setting up a feedback loop (FBL) with the ISPs that provide
this service, you will receive a copy of each complaint generated
when this happens, and the recipient will usually be unsub-
scribed from your list automatically.
As with a whitelist, an FBL means that you’re taking responsibility
for your email practices. Monitoring FBLs benefits both mailers
and ISPs, in that they help to manage mailing lists as well as
providing early warnings of network security issues.
Major ISPs providing FBL include:
Gmail
Hotmail
AOL
Yahoo!
Comcast
Cox
Road Runner
Feedback Loops
[ Technical Requirements ]

23. 23
The final major factor in optimizing email deliverability and
maintaining best practices is the type of sending platform or
infrastructure you use to send email campaigns and transactional
messages. Senders have more choices today than ever, from
open source MTA products, to advanced commercial platforms,
to cloud offerings.
SparkPost leads all competing options by delivering the indus-
try’s best inbox placement — 97.8%. SparkPost’s deliverability is
8% better than the runner-up, and 15% higher than the average
inbox placement in the industry. Senders leveraging SparkPost
see more of their email reaching their intended recipients — this
kind of successes manifests as improved deliverability and a
higher return on investment.
Email Delivery Platforms
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
SendGrid
Dyn
Mandrill
Amazon SES
Mailgun
Google App Engine
Cloud Provider Deliverabilityvi
68.6%
69.8%
83.6%
86.9%
87.2%
89.5%
97.8%
Inbox Placement Percentage
Cloud Provider Deliverability

24. 24
Adaptive DeliveryTM
Maintaining world-class deliverability at scale requires a level
of competence in understanding the characteristics of email in
transit, the signals ISPs read to identify spam, and architecting
systems compliant with industry established best practices.
SparkPost built the Adaptive Email Network (AEN) to help auto-
mate delivery to more than 12,000 global ISPs and mailbox
providers. The AEN intelligently categorizes bounces, throttles
email traffic in real time in response to sending conditions as
they arise, and maintains over 2000 rules that optimize the
delivery and sending of email.
Adaptive Email Network

25. SparkPost.com • 301 Howard St., Suite 1330 • San Francisco, CA 94105 • tel +1 415-578-5222 • toll free usa 877-887-3031
©2015 Guide_Email-Best-Practices_0915
The potential value and ROI of email messaging is too important to leave to chance.
Applying the best practices discussed in this e-book will help you achieve the highest
possible inbox rates and help every message you send translate into a real bottom-line impact.
Contact Us Today to ensure your messages get through.
Visit us online at sparkpost.com and follow us on Twitter @SparkPost.
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