Email signature glossary
The terms you meet when setting up email signatures, explained in plain language.
- Alias
- An extra email address that delivers to and sends from the same mailbox.
- Bidi (bidirectional text)
- Text that mixes right-to-left and left-to-right runs, such as Arabic with phone numbers.
- Centralized Deployment
- The Microsoft 365 admin feature that installs an Outlook add-in for users or groups.
- Click-through rate (CTR)
- Clicks divided by impressions, shown as a percentage.
- Dark mode inversion
- How mail apps recolour emails, including signatures, when dark mode is on.
- Domain-wide delegation
- A Google Workspace permission that lets an approved app act on users’ settings across a domain.
- Email disclaimer
- A short legal or informational notice at the end of an email.
- HTML signature
- A formatted email signature built from HTML so it can include layout, links and images.
- Image proxy
- A service an email provider uses to fetch and cache images on the reader’s behalf.
- Impression pixel
- A tiny invisible image used to estimate how often a signature is seen.
- Retina image
- An image saved at twice its display size so it stays sharp on high-density screens.
- RTL (right-to-left)
- Scripts such as Arabic and Hebrew that are read from right to left.
- sendAs
- The Gmail setting that holds each sending address and its signature.
- Transport rule
- A mail-server rule that changes messages in transit, sometimes used to stamp signatures.
- vCard
- A standard contact-card file (.vcf) that adds someone to an address book.