MailMum Glossary

Bounce Message or Report

A bounce report, also known as a bounce message or a non-delivery report (NDR), is an automated email message generated by an email server to inform the sender that their email was not delivered to the recipient’s inbox.

Why an email can’t be delivered?

When an email is sent, it is routed through various servers before reaching the intended recipient’s mailbox. If there is a problem with the delivery of the email at any point in this process, such as an incorrect email address, a full mailbox, a blacklisted server, or a blocked email domain, the email may “bounce” back to the sender.

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Email Service Provider (ESP)

An Email Service Provider (ESP) is a third-party company that offers email hosting and management services, allowing users to send, receive, and manage emails. ESPs typically provide services by managing email servers and other related systems.

Who can be an email service provider?

An Email Service Provider (ESP) can be any person, company or organization that provides email hosting and management services. This can include:

In general, any person, company or organization that has the infrastructure and expertise to provide reliable and secure email services can be an Email Service Provider (ESP).

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Geofeed

Geofeed is a collection of IP networks accompanied by geolocation information that is typically distributed in CSV format via an http(s) link. These links are usually exchanged informally among trusted parties.

What is the format of a Geofeed?

Geofeeds are published using https URLs using CSV file format. It consists of four values per line:

By example such a feed can look like:

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Internet Service Provider (ISP)

An Internet Service Provider (ISP) is a company that provides internet access to customers. It does this by providing a connection to the internet via a network of servers, which allows users to access the web, send emails, and use other internet services. ISPs can be large, national companies or smaller, local providers.

Do ISPs provide email services?

Some Internet Service Providers (ISPs) do offer email services to their customers as part of their internet package. This means that when you sign up for internet service with a particular ISP, you may also be given a unique email address that you can use to send and receive emails. However, not all ISPs offer email services, and you may need to use a separate email provider, to create and manage your email accounts.

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IP Block Listing or Blacklisting

IP blacklisting is a technique used by Internet Service Providers (ISPs) and email providers to block or filter incoming messages from IP addresses that have been identified as sources of spam or other malicious activity. By blocking or filtering messages from these IP addresses, ISPs and email providers can help protect their users from spam and other unwanted email.

IP Blacklisting on local systems

IP blacklisting can be applied using configuration files in several different ways, depending on the specific needs of the organization and the type of system that is being used. Here are a few examples of how this might be done:

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Mail Transfer Agent (MTA)

An Mail Transfer Agent (MTA), is a software application responsible for the of email messages between computer systems. The MTA is a critical component in the email delivery process, ensuring that messages are routed correctly from the sender to the recipient.

What is the role of an MTA?

The primary role of an MTA is to accept incoming email messages from a client application or another MTA and deliver them to the appropriate recipient. This process involves routing the message through the internet or a local network, resolving any addressing issues, and ensuring that the message is delivered successfully.

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Pointer Record (PTR)

A PTR record (Pointer record) is a type of DNS record used to map an IP address to a domain name (e.g. 127.0.0.1 -> localhost). It enables reverse DNS (rDNS) lookup, allowing you to find the associated domain name for an IP address.

What is a Pointer Record (PTR) used for?

A PTR record is used for reverse DNS lookups. It associates an IP address with a domain name, enabling identification of the domain name associated with a given IP address. PTR records are commonly used for verifying server identities, preventing email spam, and troubleshooting network issues.

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Reverse DNS (rDNS)

Reverse DNS (rDNS) is a technique used to map an IP address to a domain name using a Pointer (PTR) record. It involves querying the DNS system in reverse, starting with the IP address, to retrieve the associated domain name(e.g. 127.0.0.1 -> localhost). Reverse DNS is commonly used for verifying server identities, preventing email spam, and troubleshooting network issues.

What is a reverse DNS record used for?

A reverse DNS record, also known as a PTR (Pointer) record, is used for reverse DNS lookups. It associates an IP address with a domain name, enabling identification of the domain name associated with a given IP address. Reverse DNS records are primarily used for verification of server identities, preventing email spam, troubleshooting network issues, and establishing trust in various online services.

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Top Level Domain (TLD)

A Top Level Domain (TLD) is the last segment of a domain name, representing the highest level in the domain name system. It typically consists of two or more letters and indicates the purpose or geographical location of a website or entity. Examples include .com, .org, and .net. TLDs help categorize and organize websites on the internet, facilitating easy navigation and identification.

Here is a list of some typical Top Level Domains (TLDs) and their envisioned use cases:

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