What is the proper time delay between sending emails for SMTP to not fail on Windows Server 2008 R2 machines?
For example, if I set a 500ms delay, would it successfully send all emails?
My software will send announcement email to my players. i can send all emails without any delay or i can make the software sleep like 500ms for each sending email
Answer
If your software follows the RFCs no delay is required. You should be able to send multiple emails in the same connection without delays.
If your software just sends messages and relies on delays rather than following the RFCs, there is no correct answer.
EDIT: If you read the RFCs you will see mail is sent using a conversational protocol. If your software follows that protocol, there is no need to insert delays between messages. Some software just uses delays where it should be following the conversation. Software that does that is very fragile and may break if the other end does not respond within a reasonable time.
Adding delays between messages when you send a bunch may or may not be a good thing. Delays give the server time to process the last message before a new message arrives. Not having a delay increases the chance that multiple messages can be sent upstream with one connection. Unless you overload your mail server I would opt for no delay.
Attribution
Source : Link , Question Author : MonsterMMORPG , Answer Author : BillThor
