When Mailster sends an email via your chosen delivery method it always relies on the response of your sending server. Sometimes the message has been sent but not actually delivered.
Sendmail is a mail transfer client which is used by many providers Sendmail isn’t designed for bulk mailings in the first place. However, you can still use it for this purpose. Some providers have limits so you may have successfully sent emails via Sendmail and it suddenly throws that error. If you like to bypass […]