C # using the System.Net.Mail wrote email program automatically,
Most of the mail can be normal to send, the same wholesale to send mail, there is always a few letters sent failure, not send failure rule, the same recipient, sometimes can send success sometimes send failure, today may be the email address, tomorrow may be another email address,
Sometimes The error message is: The operation has timed out, I can understand this,
Most of the error message is: Failure sending mail, do not know to have who know that this error message may be related to what?

CodePudding user response:

Universal way is to sleep 500 milliseconds between email try,