Email Message Headers

GemBox.Email provides an advanced API for manipulating email messages in your C# and VB.NET applications via the GemBox.Email.Mime namespace.

The message headers contain essential information related to the content of the message and store various email metadata, like a priority, spam score, etc. You can retrieve them via Header objects.

The MailMessage object contains properties for required and commonly used message headers, such as MailMessage.Subject, MailMessage.Sender, etc.

It’s also possible to add and remove headers from the HeaderCollection collection.

The example below shows how you can modify header values manually or through provided properties. It also shows the link between headers and properties and how they are updated automatically.

Email headers in C# and VB.NET
Screenshot of updated email headers and properties
using System;
using GemBox.Email;
using GemBox.Email.Mime;

class Program
{
    static void Main()
    {
        // If using Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        // Create new message.
        MailMessage message = new MailMessage("sender@example.com", "receiver@example.com");

        // Get 'From' property and 'From' header.
        MailAddressCollection fromAddresses = message.From;
        Header fromHeader = message.MimeEntity.Headers[HeaderId.From];

        Console.WriteLine($"Original 'From' property value: {fromAddresses}");

        // Change 'From' header value.
        fromHeader.Body = "new.sender@example.com";

        Console.WriteLine($"Modified 'From' property value: {fromAddresses}");

        // Get 'To' property and 'To' header.
        MailAddressCollection toAddresses = message.To;
        Header toHeader = message.MimeEntity.Headers[HeaderId.To];

        Console.WriteLine($"Original 'To' header value: {toHeader.Body}");

        // Change 'To' property value.
        toAddresses[0].Address = "new.receiver@example.com";

        Console.WriteLine($"Modified 'To' header value: {toHeader.Body}");
    }
}
Imports System
Imports GemBox.Email
Imports GemBox.Email.Mime

Module Program

    Sub Main()

        ' If using Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY")

        ' Create new message.
        Dim message As New MailMessage("sender@example.com", "receiver@example.com")

        ' Get 'From' property and 'From' header.
        Dim fromAddresses As MailAddressCollection = message.From
        Dim fromHeader As Header = message.MimeEntity.Headers(HeaderId.From)

        Console.WriteLine($"Original 'From' property value: {fromAddresses}")

        ' Change 'From' header value.
        fromHeader.Body = "new.sender@example.com"

        Console.WriteLine($"Modified 'From' property value: {fromAddresses}")

        ' Get 'To' property and 'To' header.
        Dim toAddresses As MailAddressCollection = message.To
        Dim toHeader As Header = message.MimeEntity.Headers(HeaderId.To)

        Console.WriteLine($"Original 'To' header value: {toHeader.Body}")

        ' Change 'To' property value.
        toAddresses(0).Address = "new.receiver@example.com"

        Console.WriteLine($"Modified 'To' header value: {toHeader.Body}")
    End Sub
End Module

The GemBox.Email Header class follows the RFC 5322 standard. A header is made of two parts, a name, and a body. The first part (name) cannot be empty while the body can be.

GemBox.Email supports adding both standard and custom headers. To add standard headers, use the HeaderId identifiers.

The following example shows how you can add additional headers to an email message.

using GemBox.Email;
using GemBox.Email.Mime;

class Program
{
    static void Main()
    {
        // If using Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        // Create new message.
        MailMessage message = new MailMessage("sender@example.com", "receiver@example.com")
        {
            Subject = "Example Message",
            BodyText = "High priority email with comments."
        };

        // Add message comments.
        message.MimeEntity.Headers.Add(
            new Header(HeaderId.Comments, "Example of mail message comment"));

        // Add message priority.
        message.MimeEntity.Headers.Add(
            new Header("Importance", "high"));
        message.MimeEntity.Headers.Add(
            new Header("Priority", "urgent"));
        message.MimeEntity.Headers.Add(
            new Header("X-Priority", "1"));

        message.Save("High Priority Message.%OutputFileType%");
    }
}
Imports GemBox.Email
Imports GemBox.Email.Mime

Module Program

    Sub Main()

        ' If using Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY")

        ' Create new message.
        Dim message As New MailMessage("sender@example.com", "receiver@example.com") With
        {
            .Subject = "Example Message",
            .BodyText = "High priority email with comments."
        }

        ' Add message comments.
        message.MimeEntity.Headers.Add(
            New Header(HeaderId.Comments, "Example of mail message comment"))

        ' Add message priority.
        message.MimeEntity.Headers.Add(
            New Header("Importance", "high"))
        message.MimeEntity.Headers.Add(
            New Header("Priority", "urgent"))
        message.MimeEntity.Headers.Add(
            New Header("X-Priority", "1"))

        message.Save("High Priority Message.%OutputFileType%")
    End Sub
End Module

See also


Next steps

GemBox.Email is a .NET component that enables you to read, write, receive, and send emails from your .NET applications using one simple API.

Download Buy