c#异步发送邮件的类

首先要定义一个邮件信息的基类，如下所示：

/// <summary>
/// base message class used for emails
/// </summary>
public class message
{
#region constructor
/// <summary>
/// constructor
/// </summary>
public message()
{
}
#endregion

#region properties
/// <summary>
/// whom the message is to
/// </summary>
public virtual string to { get; set; }

/// <summary>
/// the subject of the email
/// </summary>
public virtual string subject { get; set; }

/// <summary>
/// whom the message is from
/// </summary>
public virtual string from { get; set; }

/// <summary>
/// body of the text
/// </summary>
public virtual string body { get; set; }

#endregion
}

然后定义一个邮件的发送类，使用netmail的方式发送邮件，发送邮件时采用了.net中自带的线程池，
通过多线程来实现异步的发送，代码如下：

 /// <summary>
/// utility for sending an email
/// </summary>
public class emailsender : message
{
#region constructors

/// <summary>
/// default constructor
/// </summary>
public emailsender()
{
attachments = new list<attachment>();
embeddedresources = new list<linkedresource>();
priority = mailpriority.normal;
}

#endregion

#region public functions

/// <summary>
/// sends an email
/// </summary>
/// <param name="message">the body of the message</param>
public void sendmail(string message)
{
body = message;
sendmail();
}

/// <summary>
/// sends a piece of mail asynchronous
/// </summary>
/// <param name="message">message to be sent</param>
public void sendmailasync(string message)
{
body = message;
threadpool.queueuserworkitem(delegate { sendmail(); });
}

/// <summary>
/// sends an email
/// </summary>
public void sendmail()
{
using (system.net.mail.mailmessage message = new system.net.mail.mailmessage())
{
char[] splitter = { ',', ';' };
string[] addresscollection = to.split(splitter);
for (int x = 0; x < addresscollection.length; ++x)
{
if(!string.isnullorempty(addresscollection[x].trim()))
message.to.add(addresscollection[x]);
}
if (!string.isnullorempty(cc))
{
addresscollection = cc.split(splitter);
for (int x = 0; x < addresscollection.length; ++x)
{
if (!string.isnullorempty(addresscollection[x].trim()))
message.cc.add(addresscollection[x]);
}
}
if (!string.isnullorempty(bcc))
{
addresscollection = bcc.split(splitter);
for (int x = 0; x < addresscollection.length; ++x)
{
if (!string.isnullorempty(addresscollection[x].trim()))
message.bcc.add(addresscollection[x]);
}
}
message.subject = subject;
message.from = new system.net.mail.mailaddress((from));
alternateview bodyview = alternateview.createalternateviewfromstring(body, null, mediatypenames.text.html);
foreach (linkedresource resource in embeddedresources)
{
bodyview.linkedresources.add(resource);
}
message.alternateviews.add(bodyview);
//message.body = body;
message.priority = priority;
message.subjectencoding = system.text.encoding.getencoding("iso-8859-1");
message.bodyencoding = system.text.encoding.getencoding("iso-8859-1");
message.isbodyhtml = true;
foreach (attachment tempattachment in attachments)
{
message.attachments.add(tempattachment);
}
system.net.mail.smtpclient smtp = new system.net.mail.smtpclient(server, port);
if (!string.isnullorempty(username) && !string.isnullorempty(password))
{
smtp.credentials = new system.net.networkcredential(username, password);
}
if (usessl)
smtp.enablessl = true;
else
smtp.enablessl = false;
smtp.send(message);
}
}

/// <summary>
/// sends a piece of mail asynchronous
/// </summary>
public void sendmailasync()
{
threadpool.queueuserworkitem(delegate { sendmail(); });
}

#endregion

#region properties

/// <summary>
/// any attachments that are included with this
/// message.
/// </summary>
public list<attachment> attachments { get; set; }

/// <summary>
/// any attachment (usually images) that need to be embedded in the message
/// </summary>
public list<linkedresource> embeddedresources { get; set; }

/// <summary>
/// the priority of this message
/// </summary>
public mailpriority priority { get; set; }

/// <summary>
/// server location
/// </summary>
public string server { get; set; }

/// <summary>
/// user name for the server
/// </summary>
public string username { get; set; }

/// <summary>
/// password for the server
/// </summary>
public string password { get; set; }

/// <summary>
/// port to send the information on
/// </summary>
public int port { get; set; }

/// <summary>
/// decides whether we are using starttls (ssl) or not
/// </summary>
public bool usessl { get; set; }

/// <summary>
/// carbon copy send (seperate email addresses with a comma)
/// </summary>
public string cc { get; set; }

/// <summary>
/// blind carbon copy send (seperate email addresses with a comma)
/// </summary>
public string bcc { get; set; }

#endregion
}