Improve Inbox Placement and Email Deliverability: Technical Aspects (Part 2)

Anton Shabatov - March 14, 2018 - 0 comments

The previous article has opened the topic on how you can improve your marketing campaign by covering important aspects of inbox placement and email deliverability. Last time we have disclosed the significance of:

  1. The email validation API.
  2. The double opt-in confirmation.
  3. The DKIM authentication.
  4. The SPF authentication.
  5. The DMARC authentication.
  6. The respectable DNS provider.
  7. PTR records.
  8. The FBL service.

Now we move forward to the second part of this topic. This article reveals other aspects like how many IPs you can use, how to deal with temporary errors, and other. So let’s continue our trip to the well-thought email campaign.

1. IP number limits for sending emails.

When you need to deliver a large number of emails there is no urgent need to use multiple IP addresses. However, there may be some reasons when this option is preferable. For instance, you want to send emails that need to be delivered in the particular timeframe. Also, separated IPs can be useful in case of sending different mail streams in order to create a separate reputation for each stream. For instance, you can deliver via multiple IPs transactional emails, marketing messages and newsletters, reactive campaigns and so on.

The common reason some email marketers start using various IPs is that they are not satisfied with the deliverability rates they received before. But it is not a solution as ISPs track your reputation via patterns of sending, links, addresses-receivers and many other factors. The wise approach is to detect the causes of bad reputation and eliminate them. Also, remember about warming-up period required for every IP. But do not switch between various addresses too often as ISPs may consider this as a suspicious activity and you will be blocked.

Every mail service has its own allowed volume of connections per IPs you can use safely. For example, in Gmail or Hotmail this number is 150 connections per IP. Check out the policy of domain you use for more info on this aspect. For small the recommended number is 1-2 connections, not more.

2. Re-attempt delivery of emails after temporary errors.

Firstly, we need to understand the process of email delivery. You send the email via email client that connects to your mail server. Then, the server tries to connect the receiver’s server. When it reaches the goal, the server delivers the message to the receiver and he downloads the email. However, due to the multiple step process, the delivery may fail. Such situation may be resulted by the errors of DNS, mail limits, unreachable servers and so on. This issue is known as #451 temporary local error. It leads to bouncing.

When this error occurs, your email is greylisted by your ISP. Provider expects you retry sending the email later. It has to be done via the same IP in order to avoid repeated greylisting. It can be helpful when you have configuration problems. Here is a recommended schedule for retries: in 15 minutes – the first retry, 45 for the second one, 2 hours for the third, 6 – for the fourth and 12 for the fifth.

3. Remember the about effective unsubscribe method.

You can improve your reputation in ISPs if you use the unsubscribe link in your emails. Adding such option to emails will have a positive effect on your subscribers’ reaction and reduce the number of cases you get into spam folders. Almost every mail service provides “Unsubscribe” header by default. When the user clicks on this link, the server generates a message back to your domain and commands to stop sending emails to the specific address.

4. Turn on outgoing TLS connections.

TLS, or Transport Layer Security, is a security protocol that is responsible for safe and understandable data delivery between two communicators. It is used in browsers and applications that include data exchange via a network. It has two layers Record and Shake protocols. The first one is responsible for security. The second ones enable authentication between server and client and deal with encryptions and cryptographic that appears during data exchange.

In emailing there are 4 variants of this protocol: 1.2, 1.1, 1.0 and zero TLS. Mail servers tend to use the safest option so they often neglect the zero TLS actions. This means that the deliverability rate depends on whether you have enabled TLS while distributing emails. Users of G Suite have this option turned on by default. More info about setting this protocol in Gmail read here.

5. Use public WHOIS for the domain.

The organization ICANN carries out the governmental task to collect domain names, contact info, and other owners’ data and list it in the WHOIS database. And now every user can go to the ICANN website and find out who is standing behind the particular domain. Sure thing, not every owner wants to make the contact information available to the wide audience that is why there is an option for private WHOIS. However, for email marketers, it can be not the best variant. In some countries, it is even illegal to hide behind the private domain. Mail servers also can indicate your domain as a suspicious one and your emails will start getting into spam.

There are some positive aspects of using public WHOIS. That is how you show your domain is not going to be used for unwelcomed activity, as everyone can check who the owner is and contact this person. This option can serve as an extra source of contact info for your customers as well.

6. Do not diversify emails per destination ISP.

Use this option only in urgent cases. Otherwise, you will experience the detrimental effect. The thing is that domains usually use SenderScore in order to check the reputation of IP. When you segment your emails this way they do not have a chance to get the required data due to the absence of Return-Path.

Return-Path indicates where the undelivered or bounced emails should go. This option is required when you deliver tons of emails and you need to have a particular place for storing bounce letters. You can open that box and analyze what has gone wrong in order to fix your mistakes. G Suite users are provided with this feature and you can get more info in this matter on the dedicated chapter of G Suite support.

7. Use personal IP-addresses instead of shared ones.

As we know, the IP address is read by ISPs in order to make a decision whether to deliver your email or not. The result depends on the reputation of a particular IP. So the ability to control the IP’s reputation is vital in our case. However, there are two options you can choose from: shared and dedicated IP addresses. Let’s take a closer look at each of them.

The shared IP means you use the address simultaneously with a number of other senders. It is like a corporate mail that is accessible to a group of selected users. That is the main principle of shared IPs. But there are some aspects that call in question the appropriateness of such an address for email marketing purposes. For example, you cannot control the reputation of the shared IP. Despite the fact that there is no need to warm up the address, the reputation issue can be crucial.

Personal or dedicated IPs provide you with complete control over your reputation. You can monitor the activity of your own campaign, detect the problems, fix them and watch the positive results of your campaign. There are no any risks other sender’s activity affects your deliverability rates. Also, this option is preferable for senders who deliver more than 100k per year.

Some marketers start with shared addresses with the intention to move to a dedicated one. It is a forced measure in order to grow their business. But we strongly recommend avoiding the shared addresses and switching to the personal IPs as soon as you can.

8. Take care of valid MX records for your domain.

MX (or mail exchanger) record is the type of record in DNS that show what mail server is accountable for receiving emails by addressee’s domain and select the preferable one when there are a few available servers. Those records in domain define the destination of email via SMTP. According to RFC documentation when the particular MX record is invalid, the A record should be considered as a mail server. In reality, we can observe that some providers do not follow this statement and check the MX record before accepting email from the particular domain. So you need to be sure this record is valid. Check it via MXToolbox. In order to be sure in this aspect, select respectable mail services like G Suite, provided by Google.

The bottom line

This article closes the chapter about technical aspects that affect your deliverability rates. However, this is not the only factor that leads to good or bad campaign performance. The reputation of your brand and domain also depends on the quality of the content you send. That will be the topic for the second chapter of our guide. Stay will us and you will not miss next useful materials.

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