Bulk email terms 101

Wondering what a marketing campaign, ESP, transactional email, domain reputation, and more are?
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When you decide to promote your business or brand online, you will start seeing many different terms. You may wonder what a marketing campaign, ESP, transactional email, domain reputation, and more are. While they are all related to bulk email, they do not all mean the same thing. Fortunately, they are simple to explain, and we have spelled out the basics right here. Once you see the differences between each term, you will be ready to start an email marketing campaign with ease.

Bulk email


It is merely a process or act of sending an email message to many email addresses at once.

Mailing list

It is a list of email addresses. You will probably want to include additional information about each contact, like name, phone number, user account, etc. The most basic way of managing a mailing list is to have a spreadsheet file.

Email marketing campaign.

Personalized email messages sent to a group of contacts for some purpose is an email marketing campaign. It would be best if you defined a timeframe and the goal of a marketing campaign in advance.

Types of mass email messages


You will send a newsletter email when you want to inform your subscribers about something. It may be a new blog post, an event you just held, or a new product. A newsletter usually has a single main topic.

Transactional email

When people make a payment or register on your site, you would probably want to inform them that the action was successful. A transactional email is a message telling about the state related to their account. It can be an invoice, a welcome letter, password change notification, or anything else that you think might help your users.

Sender reputation

Sender reputation is a score between 0 and 100. Mailbox providers like Google and Yahoo keep a history of sender reputation. If you send spam, your sender reputation goes down. And the other way around, if users engage with your emails and do not mark them as spam, your sender reputation goes up. When a sender attempts to deliver an email, an email server checks the sender's reputation. The email server then decides whether to accept, reject, or deliver an email to the user's inbox or spam folder.

An email service provider (ESP)

It is a third-party service you use to send mass emails to your marketing list.

Spam complaints

When users encounter an email that they consider spam or unwanted, they are most likely to report it as spam. Users file a spam complaint by marking an email as spam.

Hard bounces

Email messages not accepted by an email server due to some reason are hard bounced. The most common causes of hard bounces are low sender reputation and an inexistent mailbox.

Soft bounces

Unlike the case with hard bounces, an email server will accept a message despite bad sender history or an invalid email address. An email server later sends back an undeliverability email report. The returning email is a soft bounce.


When the sender's reputation becomes too low, the sender gets blacklisted. From now on, a mailbox provider will hard bounce all emails from the sender.

A feedback loop (FBL)

When a user marks an email as spam, a mailbox provider may notify the sender that there was a spam complaint. Thus, the sender gets feedback on the number of emails marked as spam.

Deliverability rate

Deliverability rate is a ratio of delivered to bounced emails of the marketing campaign or the timeframe.

Email verification

Email verification is the process of checking email addresses on a mailing list. It verifies each email address one by one and removes invalid addresses from a mailing list. Email verification helps prevent undesired outcomes like bounces and blacklisting. The service connects to a mailbox provider server and tries to deliver an email to the address without sending a message. It checks the server response. If the server responds with an error, the verification service removes the email address. Email verification services usually give extra information and suggestions on each email address.

Verify email address

We do not store email addresses you check.

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