Blacklist: A blacklist contains a set of IP addresses that are suspected of sending out unsolicited email (spam). If your sending IP has a high complaint rate, high hard-bounce rate, or a bunch of spamtrap addresses (see term No. 16), you are more likely to be blacklisted.
Bounce: An email that is rejected by the receiving mail system is said to have bounced. An email can be returned as “bounced” for many reasons, such as having an unknown alias (username), nonexistent domain name, or full inbox. (See more in the “Hard Bounce” and “Soft Bounce” sections.)
CAN-SPAM Act of 2003: Signed into law in December 2003 by President Bush, CAN-SPAM establishes the standards for sending commercial email in the United States.
Click-through rate: Similar to open rate (see No. 12), CTR can be measured different ways. The most common, however, is clicks divided by emails sent. For example, if you sent an email to 100 people and 12 of them clicked on one or more links, your click-through rate would be 12%.
Cost per thousand (CPM): Most of the major ESPs charge email marketers based on the number of emails sent per given time period (month or year). Rates are based on 1,000 emails. Typical CPM rates can range anywhere from a few cents to several dollars, based on overall volume.
Deliverability: The number of emails that are sent minus those that bounce equals deliverability. See more under “Inbox Deliverability Rate.”
Email service provider (ESP): An ESP is an organization that provides a tool or service that enables marketers to send out mass emails to their clients, prospects, and customers. Many ESPs also provide strategy and consulting services.
Hard bounce: A hard bounce is an email that does not reach the intended recipient because of some permanent error. In server-speak, it’s defined by a 5xx error code. Hard bounces can occur when an alias (username) or domain does not exist. In most cases, emails that have hard-bounced will never be delivered.
Inbox deliverability rate: This term refers to the proportion of emails that reach the intended recipients’ inboxes for a given email campaign. Put another way, it’s determined by emails sent minus those that bounced, dropped, lost, blocked, filtered as spam, etc.
List purchase: Buying an email list normally involves not only an exchange of money but also an actual handover of an email list (a file). Buying a list means that you, the list buyer, actually purchased the list. It’s yours. You can do with it as you please.
List rental: As opposed to buying a list, renting a list does not allow for an exchange of list ownership. Instead, the list renter is merely using the list owner’s email addresses to send a targeted message.
Open rate: Essentially, open rate is the number of emails opened compared with the number sent. In other words, if you send a campaign to a list of 100 addresses, and 22 emails were opened, you’d have a 22% open rate.
Not all ESPs measure open rate the same way. Some count a click as an “open.” Some count those delivered (sent minus bounced) as the denominator. It gets even stickier if you consider that “opens” are really just a measure of an email that’s rendered in one’s inbox, and so does not necessarily mean the message has been read. (The industry is moving to standardize the way open rates are measured.)
Permission-based email marketing: Asking for, and obtaining, permission to email subscribers is the basis of permission marketing. Most often, subscribers will check a box to give you consent (permission) to send them emails.
Soft bounce: A soft bounce is an email that does not reach the intended recipient because of some temporary error. In server-speak, it’s defined by any error code other than 5xx. Note that sometimes the mail server will not return an error code at all. Typically, soft bounces are due to full inboxes or temporary “hiccups” by mail servers or ISPs.
Spam: We all know spam when we see it. Typically, spam is email that is unsolicited or email that we didn’t sign up (opt in) to receive.
Spamtrap/honeypot: These are old/inactive/unused email addresses that are intentionally set up to catch spammers. If you have spamtrap/honeypot email addresses on your list, it may be time to review your process for growing your email list.
Whitelist: A whitelist is a list of “approved” IP addresses and senders. If an Internet service provider (ISP) has whitelisted an IP address, it is more likely to accept incoming email from that address.