Optimizing deliverability by emailing:
Best practices

Almost 20% of commercial emails never reach recipients, deliverability is a term used in e-marketing. Its definition is the rate of emails that arrive in the mailboxes. Given the tightening of the rules of the ISPs and the webmails to fight SPAM, the deliverability of the emailings becomes a fundamental point in its communication mail. Without caution, a simple newsletter can be considered as SPAM and make you consider as spammer (your domain and IP).

The essential steps to ensure good deliverability


How to ensure that your emails are not considered as SPAM?

Work your reputation with ISPs (Internet service provider). Your deliverability depends mainly on the quality of your mailing lists and your sending rules and frequencies. ISPs will assign a "Sender score" to your shipments. Between 0 and 100, depends on the percentage of your emails arrived in inbox. Under 60, your emails will go directly into SPAM box, under 30, they will not even leave.

How to ensure a good sending reputation ?

Clean your database

The quality of your email addresses is essential for your deliverability rate. A rate of bounces greater than 10% will have an immediate role on your reputation score. The consequences will not be delayed and you risk a deliverability rate lower than 50%. It is therefore necessary to clean your databases of hard bounces, soft bounces and inactive addresses (no opening or clicking on the emails) because some ISPs use them as addresses for spamtraps or trap addresses. Start cleaning your databases with Captain Verify and you will have an email database clean and ready to send.

Avoid complaints

Think about highlighting a unsubscribing link. It is better to put it at the top of the email to allow your subscribers to simply unsubscribe. This will prevent them from considering your emails as SPAM. Please specify the sender and the reason for receiving the email.

How often and what IP?

This notion is subjective. It depends on the emails you send and their content. For advertisements, the acceptance threshold is estimated at 4 emails per week to avoid unsubscriptions and complaints. Then, if you want to master your reputation, we advise you to use dedicated IPs. Shared IPs can be double edged.

Watch out for blacklisting!

It is important to follow all the good rules of sending emails to avoid complaints. If you accumulate too many complaints, your IPs could be considered Spam. You will be considered as spammer and your mails will no longer be sent, blocked by the ISPs who work with its databases. There are also certification programs allowing you to be on whitelister lists. These Sender Score Certified programs are often very expensive and take a long time before getting a validation. Moreover, they do not guarantee you a permanent whitelistage. It is better to maintain your database with a meticulous cleaning and to tweak the contents of your emails.

Caring for your emails content

The content of an email is essential to ensure deliverability. Everything is important, the html code as well as the contents of the email. Avoid fancy and special characters in the subject of the sending. Then, choose wisely the vocabulary you use, as some words are directly classified as spam like terms with sexual character and words like: free, cheap, etc ... Also think to balance the proportion images / text. Ideally, more texts than images are needed. We must proscribe the emails only composed of a large image. Encoding your email in utf-8 is what will go best under all browsers. Do forget to make tests (litmus.com).

You will find online software to test your emails (spamassassin): the content, the html, the responsive. A result greater than 5 means that your email is not good and will be considered as spam. Do not hesitate to test before sending and to correct your errors.


Want to improve your deliverability? Have you ever verified your recipients? It’s easy! Simply register on CaptainVerify to benefit from our expertise. Our online service will very quickly carry out a check and clean up your email marketing list. Captain Verify offers a wide choice of checks based on your needs at very low rates.

Sign up now to improve your deliverability