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How do I prevent or minimise the risk of my emails going to SPAM?


Is there a way to schedule the emails to reduce the likelihood of the email server being flagged as a spammer? For example, if we have 500 emails to send and they all go at once that will likely trigger a 'black list' event.




In answering it I won’t focus on scheduling the emails in batches as this feature is not immediately available in PDF-eXPLODE at the moment; but we are working on it for the next version at the end of this year. However the root cause of spam and resulting blacklisting of one's server(s) can result from other factors as outlined below.   Below we suggest you look at your actual email sending from any programming tool (like PDF-eXPLODE) and how you can make it 99.9% safe


The Prevention of a SPAM classification of your sent Emails can be divided into two distinct areas:     

  1. Subject and Email content of message
  2. Use of validated/authenticated Sender address   


CASE 1: Subject and Email content of message

 If your email is marked as spam by a recipient, more scrutiny is placed on your future emails by their filters. Hence use the following tips to prevent or limit the risk of genuine emails being marked as “SPAM/JUNK”



  2. D o n t   p u t  g a p s  b e t w e e n  l e t t e r s  a n y w h e r e !
  3. One exclamation marks works fine, don’t go crazy!!!!!!!!!1!!!!!!
  4. Stay away from words and phrases that sound gimmicky: Buy Now, Click Here, Free, As Seen On, Double Your X, Money Making, Get Paid, Make Cash, Pre-Approved, Satisfaction Guaranteed, Low Price, Save Big, etc.
  5. Encourage subscribers to whitelist/add you as a contact, and personalize your ‘To’ field with the recipient’s name.
  6. Be sure your ‘From’ name is relevant to your business/site to prevent confusion.
  7. Keep images minimal. Having more space in the body of an email taken up by images than by text raises lots of red flags. Aim for a high text to image area ratio.
  8. Be very careful about the quality and quantity of links in the content. Keep the number of links minimized and don’t use URL shorteners.  


   MASS CIRCULARS (Like Newsletters and Price lists)  

  1. Give a clear and obvious opt-out feature from future emails and follow through promptly.
  2. Reach out to inactive subscribers and keep your contact lists whittled down to those who want to hear from you. This can reduce the likelihood that folks that have lost interest will just mark you as spam to stop the emails because it’s faster than unsubscribing. Their “Mark As Spam” classification may get relayed to their server.  


CASE 2: Use of validated/authenticated Sender addresses    

If your sender email address and domain is validated then the risk of your server being blacklisted is low and emails won’t be classified as SPAM in 99.9% of the time. This means you need to learn a bit about how to create an SPF or DKIM record, and set them up in your DNS ( Domain Name Service ) records for your mail server, if you want to have a better control over your email deliverability.


What is SPF?                  

Sender Policy Framework (SPF) is a security mechanism created to prevent spammers from sending emails  with a Sender address that seems to come from your domain. The mechanism is all about communication between DNS servers.

Let’s say you’ve sent an email to Bob. You have SPF set on your DNS server .  SPF defines which IP addresses can be used to send emails from your domain. So Bob’s DNS server knows that the email was in fact sent by you if the incoming email is from the IP address defined in the SPF record.  So let’s imagine two possible server “conversations”. To make it all easier, let’s assume your name is Mike.


Scenario 1 – You don’t have SPF set up.   

Mike’s server: Hey, Bob’s server. I’ve got a new message from Mike.
Bob’s server: Hi Mike’s server. What’s your SPF?
Mike’s server: Yeah, about the SPF… Who cares, really. I don’t have one. Trust me, it’s from Mike.
Bob’s server: If you don’t have SPF, I can’t be sure it was Mike who sent this. Give me Mike’s allowed IPs, so I can compare it with yours.
Mike’s server: I don’t have the list of Mike’s allowed IPs.
Bob’s server: Then I don’t want your message. Delivery denied. I will mark this as SPAM.


Scenario 2 – You do have SPF set up.   

Mike’s server: Hey, Bob’s server. I’ve got a new message from Mike.
Bob’s server: Hi Mike’s server. What’s your SPF?
Mike’s server: here’s my SPF. There’s a whole list of IPs that Mike himself declared as the ones which can be used on his behalf.
Bob’s server: Ok, let me see… And the message you have for me is sent from IP Ok, it’s on the list. Everything looks fine. Give me the message, I’ll show it to Bob. Thanks!   


How to set SPF on your server?   

The general idea is to make sure all applications that send emails on your behalf (and are using their own SMTP, not yours) are included in your SPF. For instance, if you’re using Google Apps to send emails from your domain, you should put Google in your SPF. Here’s  Google’s instruction  on how to do this.

But it’s important to make sure, if Google is the only app that you should “allow” in your SPF. For instance, if you are using MailChimp to send your newsletters and PDF-eXPLODE to send invoices you include the IP addresses from where these outgoing documents are sent in your SPF.  


What is DKIM?   

Domain Keys Identified Mail (DKIM) standard has been created for the same reason as SPF: to prevent the spammers from impersonating you as an email sender. It’s a way to additionally sign your emails in a way that will allow the recipient’s server check if the sender was really you or not. By setting DKIM on your DNS server, you’re adding additional way to tell your receivers “yes, it’s really me who’s sending this message”.   

The whole idea is based on encrypting and decrypting each  additional signature, put in the  header  of your message. To make that possible, you need to have two keys:   

the  private key  - which is unique to your domain and available exclusively to you. It allows you to encrypt your signature in the header of your messages.   

the  public key  - which you add to your DNS records using DKIM standard, in order to allow your recipient’s server retrieve it and decrypt your hidden signature from the header of your message

  [above information on SPF & DKIM was sourced from: https://blog.woodpecker.co/cold-email/spf-dkim/ ]


How to create a DKIM Record?

Create a DKIM record : https://www.dnswatch.info/dkim/create-dns-record  

In summary, an SPF record on your DNS means setting valid IP addresses for each corresponding email sender address being used. i.e. [IP Address] configured,  is the only valid address(es) for a particular sender email. Whereas, a DKIM identifies the only valid sender address like for instance:  payroll@Offshore.com or HR@3000AD.com   etc.  The messages from these addresses will be encrypted using a special “private key” when sending and a “public key” is included for the recipient to decrypt the message.






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