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Lost in all the technical jargon? Find definitions for common email and technical terms and learn more with our related resources.


Internet Messaging Access Protocol (IMAP) is the internet standard responsible for retrieving emails from a receiving email server and placing them in recipients’ inboxes.


IDLE is an Internet Messaging Access Protocol (IMAP) extension. It allows an IMAP client to tell the IMAP server that it’s ready to accept real-time notifications and new messages. IMAP IDLE enables an email client to tell a receiving mail server it’s ready to receive an email, meaning that subscribers don’t have to hit a refresh button to “pull” new emails into their inboxes. Instead, they’ll automatically see new messages when delivered.

IP address

An Internet Protocol (IP) address is a string of numbers that identifies any device connected to a network. An IP address can be used to identify where data originates as well as its destination.  These addresses facilitate communication between networked devices.

IP warmup

Internet Protocol (IP) warmup is the process of gradually ramping up the volume of emails sent from a dedicated IP address to build a domain’s reputation among inbox service providers (ISPs). Typically, when a brand suddenly starts sending multiple emails, ISPs suspect its IP address to be “spammy” and question if the brand is truly sending high-quality content to recipients, which is why brands must warm up their IPs.

Inbound processing

Inbound processing is a feature that enables users to send inbound messages to an email service provider (ESP) like Mailgun. In our case, the Transactional API handles the processing and parsing of the inbound message and delivers the results to your web app via a webhook. This is useful because you can allow users to directly reply to your outbound messages, reducing user friction and increasing the likelihood of scoring a conversion.