Emails are delayed.

+2 votes
Our emails seems to be delayed. Is there a problem with the hosting server?
asked Mar 4, 2015 in Email Hosting by anonymous

2 Answers

0 votes
After the e-mail has been written, composed and spell checked, the send button is pressed. This causes the e-mail to be sent from the PC to a mail server known as a SMTP (Simple Mail Transfer Protocol) sever. This is usually operated by the ISP that you pay for your Internet connection or, if you are a business, the SMTP server that handles all outgoing mail. This rarely fails. If it fails it is usually because the SMTP server is down or there is a network connection issue of some sort.
Sender's SMTP Server Locates the Recipient's SMTP Server's IP Address

If the sender's domain name if different from the recipient's domain name the SMTP server cannot deliver the e-mail to the recipient. It needs to pass the message to an SMTP server that knows how to deliver the message. The sender's SMTP server tries to find the IP (Internet Protocol) address of the recipient's SMTP server. The Internet is a very busy and congested place and this request could fail. The SMTP server does not give up at that point. In fact, it will try many times times before giving up. Most SMTP servers will try for up to five days before throwing in the towel! If you are lucky, some SMTP servers will inform the sender if the message cannot be sent within 24 hours, but still it will continue to try. Eventually, if the SMTP server finds the IP address of the recipient, it can now try to pass the message on
answered Mar 4, 2015 by AfriDude (43,970 points)
0 votes

If you haven't got the mail yet, then it is somewhere ...

  • Still on your computer (You did send this, didn't you?  Did it actually go?  Are you sure?)
  • Sitting at the ISP mail server - e.g. smtp.saix.net, smtp.afrihost.co.za.  Maybe they have a lot of mail, maybe the next server is not yet in the mood to take the mail from them.
  • Sitting on the spam filter - spam filters receive the mail, and pass it on, which is usually quick.  If it's not quick though, then it could sit there for some time.
  • Received by your own server, but not yet in your mailbox.  This actually takes time, but usually you don't notice it.
  • In your mailbox, but not downloaded by you.
  • Downloaded by you, but sticking in some dark recess of your computer (e.g. your own anti-virus and spam filter).

All of the steps, except for your own computer, produce logs with time stamps that are added to the headers of the mail.  If you view the headers, you will see lines like this:

Received: from n04.lon1.karan.org (n04.lon1.karan.org [176.67.173.38])
    by mail.centos.org (Postfix) with ESMTP id 4542AA003A4
    for <centos-announce@centos.org>; Wed, 25 Feb 2015 20:08:46 +0000 (UTC)

When the mail eventually gets through to you, you can see at what time it arrived at each hop in the chain.  One of the delays will probably be inordinately long.  When you find this, you know where the delay occurred, and it's just a matter of asking why there was a delay at that point.  If you sent other mails that were not delayed, you can study the differences and start guessing the reasons.

answered Mar 5, 2015 by Bananaman (5,390 points)
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