Best Practices for ensuring Email Deliverability

This guide contains SendGrid’s recommended best practices for attaining high email delivery rates. Satisfying each of the below conditions is a great step toward resolving current or potential issues with email deliverability such as spam folder delivery or blocking.

This guide covers the following tips:

SendGrid also has an Email Deliverability Guide highlighting these and more deliverability tips.

The value of your email

Ask yourself if you're sending the right message to the right person at the right time with the right frequency.

Overall email deliverability is influenced by how your recipients interact with your messages:

  • If your messages are opened in a timely manner, images are displayed, and links are clicked, then mail providers will see you as a sender whose messages their recipients want to receive.
  • If messages pile up, remain unopened, or get marked as spam, mail providers won't be as comfortable placing your messages in the inbox or accepting them at all.

CAN-SPAM adherence

The Controlling the Assault of Non-Solicited Pornography And Marketing Act (CAN-SPAM) was passed in order to establish commercial email standards in the US. It's very important to ensure your emails meet CAN-SPAM requirements. Some key takeaways include:

  • Don't deceive your recipients. Be up front with who you are and what kind of messages you are sending.
  • Provide your recipients with a way to opt-out of messages.

We recommend all users familiarize themselves with the email requirements outlined in the CAN-SPAM act. You can read the full text here: CAN-SPAM Act: A Compliance Guide for Business (

Clear opt-out

All email providers look for an unsubscribe method (or links) in all emails. Even though it may not make sense for transactional mail, it can make the difference between messages arriving in the inbox or the spam folder. Subscription Tracking automatically inserts an unsubscribe link into all your emails and maintains the Unsubscribe list.

Identify yourself

Maximum company visibility helps as well. Placing your company name in the subject line of your emails and including your physical mailing address and phone number in your email footers helps mail providers recognize you as a legitimate company and email sender. This also helps your recipients know that this message is indeed from you.

Segment your traffic

Keeping your mail streams separated can make a huge difference in the long run. Specifically, segmenting your marketing email from your transactional email is a great way to keep legitimate mail out of trouble.

Say, for example, you are sending your Daily Knitting Update emails on the same account and the same IP address as your receipts, invoices, and password resets.

The day then comes where one of your recipients simply can't take it anymore and marks every single Daily Knitting email they've ever received from you as spam. Knitting overload!

The potential fallback from this is that not only will that recipient no longer receive their important receipts, invoices, and password resets, but it then becomes possible that ALL recipients at the same domain or ISP may also run afoul of the same problem. Yikes!

Consider setting up a new Subuser account with an additional dedicated IP address specifically for your marketing email, for example:

Parent account | IP 1 | Receipts, invoices, and password resets
Subuser account | IP 2 | Marketing/Promotional emails

This simple division will keep your important email in the clear, even if one stream runs into trouble.

Encourage recipients to trust you

With email, things don't happen overnight, and magic wands are few and far between. So for the most part, the actions of your recipients are the highest voice of authority. Encouraging your recipients to do certain things can help bolster the trust ISPs have for you and your messages. Some examples can include:

Add us to your address book!

Having a recipient add your from address to their address book or trusted senders list can go a long way. More often than not, if an ISP's recipients trust a sender, they will be more lenient to similar messages to different recipients.

Star or Mark as important!

A simple inbox action like this is just another way your recipients can tell their mail providers that they want to continue seeing your messages.

If you don't receive an email right away, please check your spam folder and mark "not spam"

Adding this simple sentence to your sign-up form area can solve a lot of potential heartache. If a message you sent ends up in a recipient's spam folder, and the recipient manually goes in and pulls it out, that's fantastic! This not only helps an ISP's incoming mail filters in avoiding false positives, but also improves your standing with that ISP.

Sending adult content

If your business is adult in nature, we can send your mail to the same standards and deliverability as any of our other customers. However, we do not allow our users to send explicit content within emails. This applies primarily to images, but we reserve the right to refuse the sending of any type of content that we deem to be vulgar, pornographic, or otherwise explicit.

If you are unsure where your emails stand, please contact our support team at

Tips for click-tracked links

Our Click Tracking application can sometimes trip up spam filters. If you have click tracking enabled, we'll automatically replace the URL of any links within your email to redirect through our service. This could cause confusion for ISPs, as the link text might not match ith the updated URL.

For example, if your regular link looks like this:

<a href=""></a>

It would replaced with a much longer link with click tracking:

<a href="\_4MHh"></a>

An ISP may find this misleading, and cause them to mark these messages as spam. To get around this, we suggest using more descriptive link text in your messages. For example:

<a href="">Click to visit SendGrid</a>

Images and attachments

It's impossible to know how a receiving server treats attachments, so we recommend using HTML <img> tags to include images in your messages. Images must be hosted on your own, or on a public facing server to be included via the HTML tag.

For file distribution, we recommend linking to hosted files within the email, rather than including them as attachments. This helps to ensure that your message gets to the recipient regardless of any attachment restrictions on the receiving mail server. You can also use secure site logins or credentials to track who is coming to your site to download these files, and make sure they're only accessed by the intended recipients.

Tools of the trade

Finally, there are some great 3rd party services you can use to get an idea of how mail providers analyze your emails:

These services will analyze email you send them, and respond with a breakdown of all the positive and negative factors of your emails. This can help isolate and fix specific issues that may be sending your email to the spam folder rather than the inbox. These services are highly recommended for troubleshooting spam folder delivery. is another great resource you can use to get a good idea of how the internet email community ranks the IP address you send mail from.

Need a helping hand?

Getting into the inbox just so you can have the chance to engage with your customers often isn’t as easy as pressing “send.” Get customized advice from our team of email experts on how to optimize your email strategy. You can view the Expert Services and request a quote at this link.

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