---
title: "Introduction to Mail & Deploy Expressions"
slug: "introduction-to-mail-and-deploy-expressions"
updated: 2026-10-08T13:12:48Z
published: 2026-10-08T13:12:48Z
canonical: "help.mail-and-deploy.com/introduction-to-mail-and-deploy-expressions"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.mail-and-deploy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction to Mail & Deploy Expressions

### General

Expressions are formulas that can dynamically evaluate values at runtime; they allow to return static or dynamically calculated values.

**Example:** Let's suppose you design a Report and you use a Filter Datasource Field Action to filter a field. The values to which you filter the field are expressions which can be used to either return constant values or dynamic values (e.g. the current year, the previous year etc.).

### Syntax

Mail & Deploy expressions are written in Visual Basic .NET; however, there are many additional functions provided by Mail & Deploy which are not part of the standard Visual Basic .NET language.

### Expression Fields

You can enter expressions in all expression fields which can be identified in the following way:

### Web User Interface

An expression field in the web user interface (accessed by your web browser) looks like this: ![Image](https://cdn.document360.io/e3657e0f-d0b6-4032-8271-1f5869a7b807/Images/Documentation/image(56).png)

The ![Image](https://cdn.document360.io/e3657e0f-d0b6-4032-8271-1f5869a7b807/Images/Documentation/image(58).png) button in the expression editor can be used to insert a Placeholder or other values into the expression. The ![Image](https://cdn.document360.io/e3657e0f-d0b6-4032-8271-1f5869a7b807/Images/Documentation/image(59).png) button will open the expression editor which looks like this:

![](https://cdn.document360.io/e3657e0f-d0b6-4032-8271-1f5869a7b807/Images/Documentation/image%2835%29.png)

### Report Designer

Expression fields in the Report Designer look like this:

![](https://cdn.document360.io/e3657e0f-d0b6-4032-8271-1f5869a7b807/Images/Documentation/image%2837%29.png)

By clicking the three-dot browse button you can open the expression editor for that expression.

![](https://cdn.document360.io/e3657e0f-d0b6-4032-8271-1f5869a7b807/Images/Documentation/image%2838%29.png)

The ![Image](https://cdn.document360.io/e3657e0f-d0b6-4032-8271-1f5869a7b807/Images/Documentation/image(62).png) button in the expression editor can be used to insert a Placeholder or other values into the expression.