Introduction

Email sending is a pretty common task for almost every application. ASP.NET Boilerplate provides a basic infrastructure to simply send emails and seperate email server configuration from sending emails.

IEmailSender

IEmailSender is a service to simply send emails without knowing details. Example usage:

public class TaskManager : IDomainService
{
    private readonly IEmailSender _emailSender;

    public TaskManager(IEmailSender emailSender)
    {
        _emailSender = emailSender;
    }

    public void Assign(Task task, Person person)
    {
        //Assign task to the person
        task.AssignedTo = person;

        //Send a notification email
        _emailSender.Send(
            to: person.EmailAddress,
            subject: "You have a new task!",
            body: $"A new task is assigned for you: <b>{task.Title}</b>",
            isBodyHtml: true
        );
    }
}

We simply injected IEmailSender and used Send method. Send method has a few more overloads. It can also get a MailMessage object (not available for .net core since .net core does not include SmtpClient and MailMessage).

ISmtpEmailSender

There is also ISmtpEmailSender which extends IEmailSender and adds BuildClient method to create an SmtpClient to directly use it (not available for .net core since .net core does not include SmtpClient and MailMessage). Using IEmailSender will be enough for most cases.

NullEmailSender

There is also a null object pattern implementation of IEmailSender as NullEmailSender. You can use it in unit tests or injecting IEmalSender with property injection pattern.

Configuration

Email Sender uses setting management system to read emal sending configuration. All setting names are defined in Abp.Net.Mail.EmailSettingNames class as constant strings. Their values and descriptions:

• Abp.Net.Mail.DefaultFromAddress: Used as sender email address when you don't specify a sender while sending emails (as like in the sample above).
• Abp.Net.Mail.DefaultFromDisplayName: Used as sender display name when you don't specify a sender while sending emails (as like in the sample above).
• Abp.Net.Mail.Smtp.Host: IP/Domain of the SMTP server (default: 127.0.0.1).
• Abp.Net.Mail.Smtp.Port: Port of the SMTP server (default: 25).
• Abp.Net.Mail.Smtp.UserName: Username, if SMTP server requires authentication.
• Abp.Net.Mail.Smtp.Password: Password, if SMTP server requires authentication.
• Abp.Net.Mail.Smtp.Domain: Domain for the username, if SMTP server requires authentication.
• Abp.Net.Mail.Smtp.EnableSsl: A value indicates that SMTP server uses SSL or not ("true" or "false". Default: "false").
• Abp.Net.Mail.Smtp.UseDefaultCredentials: True, to use default credentials instead of provided username and password ("true" or "false". Default: "true").

MailKit Integration

Since .net core does not support standard System.Net.Mail.SmtpClient, so we need a 3rd-party vendor to send emails. Fortunately, MailKit provides a good replacement for default SmtpClient. It's also suggested by Microsoft.

Abp.MailKit package gracefully integrates to ABP's email sending system. So, you can still use IEmailSender as described above to send emails via MailKit.

Installation

First, install Abp.MailKit nuget package to your project:

Install-Package Abp.MailKit

Integration

Add AbpMailKitModule to dependencies of your module:

[DependsOn(typeof(AbpMailKitModule))]
public class MyProjectModule : AbpModule
{
    //...
}

Usage

You can use IEmailSender as described before since Abp.MailKit package registers MailKit implementation for it. It also uses the same configuration defined above.

Customization

You may need to make additional configuration or customization while creating MailKit's SmtpClient. In that case, you can replace IMailKitSmtpBuilder interface with your own implementation. You can derive from DefaultMailKitSmtpBuilder to make it easier. For instance, you may want to accept all SSL certificates. In that case, you can override ConfigureClient method as shown below:

public class MyMailKitSmtpBuilder : DefaultMailKitSmtpBuilder
{
    public MyMailKitSmtpBuilder(ISmtpEmailSenderConfiguration smtpEmailSenderConfiguration) 
        : base(smtpEmailSenderConfiguration)
    {
    }

    protected override void ConfigureClient(SmtpClient client)
    {
        client.ServerCertificateValidationCallback = (sender, certificate, chain, errors) => true;

        base.ConfigureClient(client);
    }
}

Then you can replace IMailKitSmtpBuilder interface with your implementation in PreInitialize method of your module:

[DependsOn(typeof(AbpMailKitModule))]
public class MyProjectModule : AbpModule
{
    public override void PreInitialize()
    {
        Configuration.ReplaceService<IMailKitSmtpBuilder, MyMailKitSmtpBuilder>();
    }

    //...
}

(remember to add "using Abp.Configuration.Startup;" statement since ReplaceService extension method is defined in that namespace)