Hi Sachin,
It will be better if you have asked question with sample input.
Lets guess you have list of email separated with comma(,) delimiter
txtbox1.Text = @"test@test.com,abc@abc.com,amigo@amigo.com,def@def.com,rest@rest.com";
string[] emailid = txtbox1.Text.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
foreach (var email in emailid)
{
}
Note: If you have used semicolon as delimiter then change comma to semicolon in split function.
Hope this helps you a bit.
Regards,
RK