I have been warned that sending too many emails too quickly can trigger an internet email blacklist/spam filter.

I have a list of approximately 5,000 customers that I want to send a newsletter to.

I am sending 5,000 people the exact same message, it would undoubtedly look like spam in my opinion no matter what way you look at it.

I was thinking about sending 1 per second and getting it all over and done within 2 hours - but then my web host suggested I break it up into two chunks of 2,500 and place a few hours in between each batch.

How would doing that make it look any less like "spam" to these dreaded email blacklists?

Are there any other good tips for helping the messages get through without ruining my online reputation? (ip address/domain name apparently can be blacklisted?)

I do have the first and last names of everybody I will be sending the emails too so that personalization should help I would assume?


The techniques I use to identify spam have little to do with volume. They are bases more on how well the server complies with standards and best practices. 5,000 is a relatively small mailing list and shouldn't trigger spam classification. Getting your server correctly configured to use its FQDN and having PTR configured so you pass rDNS validation will get you most of the way there.

The spam filter I use triggers on content and looks for indication that the message is similar to previously seen spam. Well formatted text not selling things in a spamish way is unlikely to be blocked by the filter.

During some research into the incoming spam I posted an article on Running an Email Server. It is a bit of a rant at marketers who do everything they can to look like they are sending spam. It is mostly mailing lists (including major mailing organizations) and automated systems (including airlines, banks, and others) that tend to be poorly configured. My article on Detecting Email Forgery (which a lot of spam attempts) may also be helpful.

EDIT: If everything else is configured correctly, you should be able to send batches of up to 100 using a single connection. Your mail server should handle the batching for you if you get ahead of it.

  • Thanks Bill. You seem to be speaking in the first person there, I take it you run a blacklist or something? I keep reading about PTR and rDNS at every turn so I suppose doing that and sending an email every 10 seconds or so should work? It would take me 24 hours but it's not like I do it often.. – darkAsPitch Aug 7 '11 at 3:57
  • I run a mail server, and like all mail servers it is targeted by spam. The vast majority of the delivery attempts are Spam. Almost all of this could be blocked by requiring a valid rDNS configuration. Unfortunately, it would also block poorly configured servers from legitimate bulk mailers and automated message systems. DNS checks still allow me to block most spammers with near 0% false positives. Any false positives should be easy for the administrator to resolve. – BillThor Aug 7 '11 at 15:39

How is it that you think sending 5,000 individual emails will get you flagged as a spammer... unless all of the recipients happen to exist at the same email domain (yahoo.com, gmail.com, etc) and there are additional factors that make your email look suspicious? Do you think that some unseen entity is monitoring your outbound email queue and is going to report your ip address to some DNSBL because you happen to send 5,000 emails in a short period of time? Email volume is probably one of the least used criteria in filtering for spam.

Microsoft, AT&T, GE, BofA, etc., etc. send thousands (10's and maybe 100's of thousands) of emails everyday. How often do you think they get blacklisted? How much do you think they worry about it, based on the volume of email they send?

Thinking that you're going to wind up on a blacklist because you send a large volume of email is, sadly, a widely held misconception.

  • "widely held misconception." - music to my ears :) I really don't have much reason to worry other than being paranoid. They are all customers who have agreed to receive email from me, I have just never done this before. – darkAsPitch Aug 7 '11 at 3:53
  • "Do you think that some unseen entity is monitoring your outbound email queue and is going to report your ip address to some DNSBL because you happen to send 5,000 emails in a short period of time?" - Yes that is basically what I thought :S – darkAsPitch Aug 7 '11 at 3:58

First of all: Don't to it at all!

Second: Think of it again.

Third: Do you have a written agreement of ALL 5000 customers to send them newsletters? If not go back to step 1.

If you have an agreement then let others do the job. You are not the right person to do it. This is not a personal offense but as you are not a professional marketer you can't do it right. Are able to automatically do list washing? What's your bounce handling strategy? Do you know about your email reputation?

Let other people do it. They know what they do and in case they will destroy their reputation not yours. Delegate newsletters to eCircle, ExactTarget, Experian, MailChimp or whatever big marketer you choose. But again don't do it yourself.

When you do it yourself, your next question will be: "Many blacklists flagged me as Spammer. My important business mails don't get through. Can you help me?" And I'm going to say: "I told you that this will happen."

Read the Magill Report and in special this blog entry. Or Wise Laura's blog. Then go back to step 2.

If you still want to "newsletter" then it doesn't matter if you sent 1 mail/minute, 10 mails/second or 1000 mails/hour. Unsolicited mail keeps being unsolicited despite of the rate you blast them out.

  • They are all customers who have agreed to receive email from me, I have just never done this before. To pay mailchimp $100 just to send out one newsletter seems ridiculous when I already pay hundreds per month for a dedicated server which is fully capable of sending emails. Thank you for the links though I will read through them thoroughly. – darkAsPitch Aug 7 '11 at 3:55
  • What do you mean about "bounce handling strategy"??? I don't really care if they don't own the email any longer... I am simply sending a one-time-ever newsletter to the few thousand people who have signed up and verified their emails through my service. I know nothing of my "email reputation" but I assume it's great since I have never spammed anybody before? :P – darkAsPitch Aug 7 '11 at 4:00
  • Then go for it. There is nothing you have to fear then. I just wanted to make you aware of possible problems. Bounce handling means that you have to care if the addresses don't exist any longer. Because sometimes old addresses transform into spam traps and suddenly there is somebody "watching" your mail. – mailq Aug 7 '11 at 9:20

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