Here is the number of code snippets that might be useful:
1. Adding subscribers:

Response.Write("
" + DateTime.Now.ToString()); MailingList list = new MailingList();
string mailinglistID = MasterFactory.GetItem("/sitecore/content/modules/mailing list/mailing lists/List1").ID;
for (int i = 1; i <= 20000;="" i++)<="" span="">
{ string name = String.Concat("Name", i.ToString());
string company = "";
string country = Sitecore.State.Language;
string email = String.Concat("Name", i.ToString(), "@company.com");
list.PutSubscriber(name, email, "", Sitecore.State.Language);
list.Subscribe(name, email, mailinglistID);
}

Response.Write("
" + DateTime.Now.ToString());

  1. Edit subscriber’s mail:

MailingList ml = new MailingList();

// getting the subscriber by e-mail XPathNavigator nav = ml.GetSubscriber("test@sitecore.net");

XmlNode node = MailingListHelper.ConvertToNode(nav);

// retrieving subscriber's info string name = node.SelectSingleNode(@"/sitecore/subscriber/name").InnerText;
string newEmail = "new@sitecore.net";
string company = node.SelectSingleNode(@"/sitecore/subscriber/company").InnerText;
string country = node.SelectSingleNode(@"/sitecore/subscriber/country").InnerText;

// adding a new subscriber with the new e-mail address ml.PutSubscriber(name, newEmail, company, country);

// deleting the subscriber with old e-mail ml.DeleteSubscriber("test@sitecore.net");

  1. Reading mailing list:

private void Page_Load(object sender, System.EventArgs e)

{

Sitecore.Modules.MailingList.MailingList mlist = new MailingList();

XPathNavigator xPathNavigator1 = mlist.GetSubscriber("at@sitecore.net");

if (xPathNavigator1 != null)

{

XPathNodeIterator xPathNodeIterator = xPathNavigator1.Select("/sitecore/subscriber");

if (xPathNodeIterator.MoveNext())

{

XmlNode xmlNode1 = ((IHasXmlNode)xPathNodeIterator.Current).GetNode();

Response.Write(MailingListHelper.GetChildValue("name",xmlNode1));

Response.Write("
");

Response.Write(MailingListHelper.GetChildValue("email",xmlNode1));

Response.Write("
");

Response.Write(MailingListHelper.GetChildValue("company",xmlNode1));

Response.Write("
");

Response.Write(MailingListHelper.GetChildValue("country",xmlNode1));

Response.Write("
");

}

}

XmlNode node = MailingListHelper.ConvertToNode(mlist.GetMailingLists());

foreach(XmlNode list in node.SelectNodes("/sitecore/mailinglist"))

{

string nameList = XmlUtil.GetChildValue("name", list);

string description = XmlUtil.GetChildValue("description", list);

string ID = XmlUtil.GetAttribute("id", list);

Response.Write("List name: " + nameList + "
");

Response.Write("Description field: " + description + "
");

Response.Write("List ID: " + ID + "
");

IMasterItem itm = MasterFactory.GetItem(ID);

if ( itm != null )

{

string forTestOnly = itm.GetFieldValue("Test");

if ( forTestOnly.Equals("1") )

{

Response.Write("For testing only is enabled" + "
");

}

else

{

Response.Write("For testing only is disabled" + "
");

}

}

}

XPathNavigator nav = mlist.GetMailingLists();

XPathNodeIterator node1 = nav.Select("/sitecore/mailinglist");

while (node1.MoveNext())

{

string name = node1.Current.Evaluate("string(name)").ToString();

string id = node1.Current.GetAttribute("id", "");

XmlNode node2 = MailingListHelper.ConvertToNode( nav );
}

  1. Read subscriber’s standard fields:

Sitecore.Modules.MailingList.MailingList mlist = new MailingList();
XPathNavigator xPathNavigator1 = mlist.GetSubscriber("at@sitecore.net");

if (xPathNavigator1 != null)
{ XPathNodeIterator xPathNodeIterator = xPathNavigator1.Select("/sitecore/subscriber");
if (xPathNodeIterator.MoveNext())
{ XmlNode xmlNode1 = ((IHasXmlNode)xPathNodeIterator.Current).GetNode();
Response.Write(MailingListHelper.GetChildValue("name",xmlNode1));
Response.Write("
"); Response.Write(MailingListHelper.GetChildValue("email",xmlNode1));
Response.Write("
"); Response.Write(MailingListHelper.GetChildValue("company",xmlNode1));
Response.Write("
"); Response.Write(MailingListHelper.GetChildValue("country",xmlNode1));
Response.Write("
"); } }