/// <summary>
/// Sends an email using the `MailKit` library.
/// </summary>
public async Task SendEmailAsync(
SmtpConfig smtpConfig,
IEnumerable <MailAddress> emails,
string subject,
string message,
DelayDelivery delayDelivery = null,
IEnumerable <string> attachmentFiles = null,
MailHeaders headers = null)
{
if (smtpConfig.UsePickupFolder)
{
const int maxBufferSize = 0x10000; // 64K.
foreach (var email in emails)
{
using (var stream = new FileStream(
Path.Combine(smtpConfig.PickupFolder, $"email-{Guid.NewGuid().ToString("N")}.eml"),
FileMode.CreateNew, FileAccess.Write, FileShare.None,
maxBufferSize, useAsync: true))
{
var emailMessage = getEmailMessage(email.ToName, email.ToAddress, subject, message, attachmentFiles, smtpConfig, headers);
await emailMessage.WriteToAsync(stream);
}
}
}
else
{
using (var client = new SmtpClient())
{
if (!string.IsNullOrWhiteSpace(smtpConfig.LocalDomain))
{
client.LocalDomain = smtpConfig.LocalDomain;
}
await client.ConnectAsync(smtpConfig.Server, smtpConfig.Port, SecureSocketOptions.Auto);
if (!string.IsNullOrWhiteSpace(smtpConfig.Username) &&
!string.IsNullOrWhiteSpace(smtpConfig.Password))
{
await client.AuthenticateAsync(smtpConfig.Username, smtpConfig.Password);
}
var count = 0;
foreach (var email in emails)
{
var emailMessage = getEmailMessage(email.ToName, email.ToAddress, subject, message, attachmentFiles, smtpConfig, headers);
await client.SendAsync(emailMessage);
count++;
if (delayDelivery != null)
{
if (count % delayDelivery.NumberOfMessages == 0)
{
await Task.Delay(delayDelivery.Delay);
}
}
}
await client.DisconnectAsync(true);
}
}
}
