Safe Senders

Microsoft mailbox setting where users can add trusted senders to reduce filtering and improve inbox delivery for those addresses/domains.


Seed List

A set of test addresses included in sends to measure inbox placement and filtering outcomes (each address is a “seed”).


Segment

A segment is a defined subset of a list (based on attributes, behaviors, or source) used for targeted campaigns.


Segmentation

The process of grouping subscribers into segments based on attributes or behavior to tailor messaging and improve relevance.


Sender Policy Framework (SPF)

A DNS record that lists which servers/IPs are allowed to send mail for a domain. Receivers check SPF results and alignment (for DMARC) to reduce forgery.


Sender Reputation

Sender Reputation is the trust score mailbox providers assign to your domain/IP based on signals like complaints, bounces, spam-trap hits, engagement, volume, and consistency.


Sending domain

The domain portion of an email address after the @ sign (including subdomains), used in identity and authentication alignment.


Sent

The state when the ESP hands off a message to the sending infrastructure/provider (e.g., SMTP relay). It does not guarantee delivery to the recipient mailbox.


Shared IP

A sending IP used by multiple senders. Reputation is influenced by all senders sharing the IP, which can help or hurt deliverability.