If you're sending thousands of emails a day through your app, or are delivering your company's newsletter to millions of people, suddenly you need to think a lot more about how your emails get sent. You'll very likely need a transactional email service, a dedicated email sending service that'll make sure your emails get delivered no matter how many you need to send.

Transactional email services—including Amazon SES, Mandrill, Mailgun, Postmark and more—let you send email messages via an API or SMTP server.

At some point, we all have been affected by our emails landing in spam or even skipping an inbox. Many clients have been lost this way, many users have looked elsewhere, disappointed. Was there a way to prevent it? Absolutely, there are many ways to improve your deliverability.   Let’s do a proper email deliverability test first.

Deliverability vs Delivery

Email Delivery refers to whether a recipient’s server accepted your email or not. If it did, it’s still not certain where a message ended up but it already counts as a positive result in a frequently seen ‘Delivery Rate’. If a message bounces for any reason (incorrect email address, the domain doesn’t exist, attachments are too heavy, etc), it counts as a failed delivery and you’re immediately notified with a "bounce back" email.

Email Deliverability, on the other hand, is about whether an email was delivered right into the recipient’s inbox or straight to their spam folder. For that reason, deliverability is often referred to as Inbox Placement. Here, a number of factors such as sender reputation, authentications or quality of content matter when automatic filters decide which way your email shall go.

In the past year, Google and Microsoft has stepped up their security due to millions of SPAM, malware and criminal intent email. To keep it plain and simple, they want to make sure the email messages originating from a website has identified itself and is reputable. Before it was a matter of not being listed on SPAM lists but now, if you don’t have the proper identification for your domain set up, the Email Delivery may not occur.

Testing for spam and deliverability

Mail-tester.com

Mail-tester.com is a free - limited to 3 tests per day or paid for unlimited - tool for analyzing emails. In a few seconds after you send an email, you have a score ready. Mail-tester looks into various factors that affect deliverability. It checks the likelihood of it going to spam and gives tips on what to improve. It analyzes your domain for most popular authentication methods and reads the HTML code of your message, continuously looking for things to improve. Finally, it checks if your domain made it to some blacklist recently which might affect your success. 

Litmus

Litmus scans your emails against 25+ different tests, identifies issues that might keep you from the inbox, and provides actionable advice for how to fix them. Tests include spam filters from inbox providers (Gmail, Outlook, Hotmail, Yahoo, etc) and webmail services, as well as score-based filters that are frequently used for corporate spam filtering. Litmus will also test email design by rendering what your email will look at in dozens of variations of desktop, mobile and web-based clients. 

MxToolbox

Authentications play a significant role in email deliverability. MX Toolbox offers various tools aimed at helping improve the domains’ capabilities. MxToolbx Deliverability is aimed strictly at validating a domain’s authentication methods. This verification is free and they also have a paid managed service as well.  You will need to send a test email to ping@tools.mxtoolbox.com. In a few minutes you will receive an email with a link to your report.

Sending

A third-party service provider can be used to help you reliably send emails from your website to your users.  These service providers are especially configured to ensure that your emails reach users’ inbox and don’t end up in the junk mail folder.

As it applies to Wordpress, a system commonly affected by poor email deliverability, WordPress is configured to send emails using the PHP mail() function. This is the primary reason why users complain about WordPress not sending email issue.  Even if the mail function is working on your WordPress hosting, sometimes your WordPress emails may still end up in spam because most spam filters will verify sender email, location, domain name, and it would flag your site email as suspicious or spam.

In many cases, the only way to fix this problem is by using an SMTP server to send WordPress emails.

Mailgun

Mailgun is a powerful email service for professional developers. With its powerful APIs, you can send, receive and track transactional emails emails easily. It has advanced email validation to increase your conversions.

It features a robust sending infrastructure with SMTP integration and a simple RESTful API to send bulk emails to your users.

Price: It’s a pay-as-you-go service. 10,000 emails and 100 email validations per month are free. For 20,000 emails and 500 email validations per month, it costs $9 / month.

SendGrid

SendGrid is a cloud-based SMTP email transactional service that comes with a reliable platform to send and receive bulk emails. Aside from sending transactional emails, they also allow you to create email marketing campaigns.

It comes with a variety of integration options for you to start sending emails. You can get a complete analytics report and real-time feedback on every email you sent.

Price: In the first month, you can send 40,000 emails for free. After that, it offers 100 emails/day free of cost forever. The essential plan starts with $14.95 / month, which includes 100,000 emails/month.

PostMark

Postmark is one of the best SMTP transactional email services that offer lightning fast delivery for your application and transactional emails. Postmark has SMTP servers distributed around the world to ensure fast email delivery.

It has an excellent tracking system that allows you to monitor how many emails are opened and how much time is spent on the email you sent.

Price: The basic plan costs $10 / month for 10,000 emails. For additional emails, you’ll need to pay $1.25 per 1000 emails.

What to do if your ip address is on a blacklist (blocklist)

Each blacklist database has its own criteria for flagging IP addresses and compiling its own list of online offenders. Those criteria could include a variety of "listings": technical, policy, and evidence-based. Each blacklist is managed by a different organization. 

If you have addressed the points above, you can reach out to each of the various providers to have yourself removed from such a list. While trying to be removed from a blacklist, follow the rules and cooperate. If you are truly innocent of any deliberate wrongdoing or if you made an honest mistake, let them know. 

In some cases with some lists, there are built-in, automatic process that removes lower-level listings (IP addresses that are light offenders) within a week or two. 

Here are a few specific resources to help:

• How to Remove Your IP from the Hotmail (or Outlook) Blacklist (https://www.rackaid.com/blog/hotmail-blacklist-removal/).  This article links to Microsoft's support request form: https://support.microsoft.com/en-us/supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75
• DNSBL provides a single place where you can check that blacklist status of your mail server's IP address on more than 100 DNS based blacklists. This service also has links to each individual service. 
• How to Remove an IP Address from a Blacklist (https://glockapps.com/how-to-remove-ip-address-from-blacklist/)