Word to the Wise: Email Best Practices

A digest of the Word to the Wise white paper Email Best Practices (Laura Atkins, 2012). The paper focuses on delivery best practices — what a sender can do to consistently reach the inbox — as distinct from communication-strategy best practices. WttW notes the paper was originally published in 2012 and that filtering has evolved since; many recommendations remain applicable, and current information lives on the Word to the Wise blog (see Deliverability Community Resources).

The Golden Rule

Send mail that recipients want and expect.

For practical purposes this dictates that all bulk email should be opt-in. Acquisition by email is still possible, but it is more complicated than buying a list of addresses and mailing it. This is the same principle developed in Foundations of Email Deliverability and Two Worlds of Email Deliverability.

A key framing: because spammers invested heavily in getting mail delivered despite poor reputations, ISPs and filtering companies built filters that look at the whole of a sender's practice. Bad practices in one stream can affect the entire mailstream, even when the sender tries to segregate good mail from bad.

General best practices

Only send opt-in mail

Opt-in means the recipient gives an email address to the sender for the purpose of receiving marketing mail from that sender. Common gray areas that are not opt-in when the sender decides on the recipient's behalf:

• Providing an email address during a purchase (is that consent to marketing?)
• Providing an address to one division of a company (is that consent for other divisions?)

This does not prohibit sending updates to customers or cross-marketing — but the sender must think about how to make sure the customer is expecting the mail.

Comply with all local laws

In the United States, CAN-SPAM requires all email to meet these criteria:

#	CAN-SPAM requirement
1	The sender must provide accurate routing information about the emails.
2	Advertising emails must be clearly labeled as such.
3	Recipients must be allowed to opt out. Opt-out mechanisms must be electronic and require only the recipient's email address and their choice to opt out — no passwords or other information may be required to process it.
4	All emails must contain the physical address of the sender.

Critical nuances:

• CAN-SPAM does not require permission. Permission is not a requirement under US law.
• Other jurisdictions require permission to send marketing/commercial email: the EU (GDPR) and Canada (CASL). Sending without permission there can create legal liability.
• In some jurisdictions permission cannot be shared or sold — even purchasing "opt-in" lists is illegal.
• Segmenting purchased lists by country to dodge opt-in laws assumes the list seller compiled the data correctly — a bad assumption. Obtaining recipient permission before sending is what actually protects the sender from inadvertently violating opt-in laws.

Practice good data hygiene

• Research indicates about 30% of email addresses are abandoned by their users every year.
• Abandoned addresses are dead weight: they pull down stats and complicate measurement of program effectiveness.
• Senders should periodically purge lists of non-responsive addresses. The specific purge rules vary by sender, product(s), and sales cycle.

Worst practices

Sending mail without explicit permission

The most widespread bad practice. Common scenario: companies automatically add purchaser addresses to marketing lists without asking — a very common source of delivery problems, especially for one-time purchases. Example failure mode: a purchaser buying a gift for someone else has no interest in future mail; they may report the sender as a spammer at a major ISP and never return to the vendor.

Buying lists

• Thousands of vendors sell "100% permission based opt-in lists"; many are nothing of the sort — harvested, compiled, or stolen.
• Because of the history of delivery problems and blocklistings caused by purchased lists, many ESPs prohibit purchased lists outright.
• Purchased lists often contain spam traps and large numbers of undeliverable addresses, driving down sender reputation.
• They are also poor acquisition tools: lists are resold repeatedly, recipients are saturated with unasked-for mail and immune to offers, and delivery problems can spill over onto the entire email program, not just the acquisition stream.

Changing domains and from: addresses

Recipient recognition drives engagement and delivery — at two levels:

• ISPs recognize senders by the combination of IP address and sending domains.
• Individual users recognize email by what shows up in their inbox (the from address).

Changes to domains, IPs, and from addresses should be planned to reduce delivery risk. (See IP Warm-Up Recommendations for the IP-change side of this.)

Affiliate programs

• Sloppy affiliates can cause major delivery problems even for a sender's opt-in mail; some affiliates hire sub-affiliates who spam on the brand's behalf without its knowledge.
• Financial incentives attract unscrupulous mailers; too much spam advertising a particular product or service can contaminate the reputation of all mail for that product or service — legitimate opt-in mail, receipts, and transactional mail included.

Conclusion — reputation tracks across streams

• The best way to reach the inbox: send mail recipients want and expect; ask permission first.
• Make clear what recipients are opting into and keep those promises — don't send daily email to someone who opted into a monthly newsletter; don't share lists with other vendors without explicit permission.
• Reputation can track across multiple mail streams. Poor practices in acquisition marketing can affect retention and transactional email. Even when senders think reputation can't be tracked and applied, it often is. (This is the case for isolating streams — see Advanced IP Segmentation — while remembering that segmentation does not launder bad practice.)