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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

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closed as not a real question by Iain, Holocryptic, Ben Pilbrow, freiheit, Bill Weiss Nov 20 '11 at 16:58

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

2  
I'm not following your question. What time delay are you referring to? Where do you set this time delay? What SMTP server are you running? –  joeqwerty Nov 19 '11 at 16:11
    
this is the delay i am going to set at my email sending software. like send email then wait 500 ms and then send the second email. –  MonsterMMORPG Nov 19 '11 at 17:36
    
This makes no sense. Either you've grasped hold of the wrong end of the stick somewhere, you've missed something very important out of your explanation or you're doing something very unusual. –  RobM Nov 19 '11 at 21:59
    
If you need a delay for SMTP not to fail, you are doing something horribly wrong somewhere. –  David Schwartz Nov 20 '11 at 3:39
    
i really don't understand you. i did not modify anything. 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 –  MonsterMMORPG Nov 20 '11 at 12:46

1 Answer 1

up vote 5 down vote accepted

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 change that multiple messages can be sent upstream with one connection. Unless you overload your mail server I would opt for no delay.

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i really don't understand you. i did not modify anything. 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 –  MonsterMMORPG Nov 20 '11 at 12:46
    
Your question was vague and got an appropriate response. See the comments to your question. I edited it and added your comment, My response has also been edited. –  BillThor Nov 20 '11 at 13:04
    
hello. thanks for editing. i will use c# 4.0 wpf application. i am using System.Net.Mail; –  MonsterMMORPG Nov 20 '11 at 13:16
    
I would expect that to follow the standards (RFCs). –  BillThor Nov 20 '11 at 13:28
    
so setting 500 ms delay is that good ? this delay will be setup at my application. i won't change anything on iis –  MonsterMMORPG Nov 20 '11 at 14:09

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