Gmail Deliverability Improvements: Tips and Tricks


One of the questions that deliverability professionals hear most often – and with good reason – is, “How do I get to the inbox at Gmail?” Over the past few years, Google has worked to establish its Gmail product as an innovator in the area of spam filtering, enacting changes that are having a notable impact across the email industry. However, many of these changes also make it harder for senders to have their mail routed to the inbox.

Just over a year ago, Chris Penn wrote a great article on the reasons Gmail provides when a message is routed to the spam folder. This is still a great resource and is a good place to start if you find your messages aren’t getting to the Gmail inbox. In many cases, though, the answer goes beyond the explanations Gmail provides. Here, we’d like to provide a bit more insight for those times that Gmail’s answer has left you scratching your head.

Get to Know Gmail

The first step in improving your mail’s performance to Gmail is to know a little about how Google filters and routes incoming mail.
First of all, engagement is key. Gmail has built a reputation on using engagement metrics to determine mail folder placement. Senders with high engagement rates are more likely to get mail delivered to the inbox, and vice versa. To put it very simply, if your users aren’t opening your emails, those emails won’t make it to the inbox.

Gmail also uses domain reputation heavily in determining how to route incoming mail, but they don’t just weigh the reputation of the domain(s) in the From and Reply-to fields. Gmail scans the entire message for any domain that appears in the headers or body of the message. The reputation of each domain in the message, including image hosting and link URLs, is considered in the filtering process.

Cracking the Inbox

There is no single change, or even set of changes, that are guaranteed to get you to the Gmail inbox. However, there are a few things you can do to improve the chances your mail is delivered there.

Target engaged contacts. Since Gmail relies on engagement in its filtering, you should identify contacts who haven’t opened any emails in a set period of time. The recommended time period will vary depending on the frequency of your mailings, but a good rule of thumb is that contacts who haven’t engaged (opened or clicked) in 6-12 months should be suppressed or removed from your sending rotation.

Get whitelisted. While Gmail doesn’t offer a traditional whitelist, there are ways you can have your recipients add you to their personal whitelists. When a subscriber adds your address to his or her Gmail Contacts, mail from that address will bypass most filtering. If a subscriber wants to ensure he or she never misses a mailing from you, Gmail also allows creating filters that will prevent any mail from a specific email address (or domain) from ever getting routed to the spam folder.

Know your affiliates. Affiliate programs can be attractive to email marketers, but they can also be a hindrance to good email deliverability. Gmail calls out affiliate programs specifically in its Best Practices for senders, noting that they sometimes attract spammers and can be harmful to your sending reputation. If you do participate in affiliate marketing, be mindful of the partners and offers included in your mailings: The reputation of every brand or company advertised in your mailing will be considered when filtering your message. Gmail also states clearly that sending on behalf of affiliates with bad mailing practices can get your mail routed to spam.

Authenticate. Gmail uses DKIM authentication to attempt to verify the identity of mail senders. If you are not signing with DKIM, your signatures don’t match, or you are using a key less than 1024 bits in length, your mail is more likely to be routed to the spam folder.

Following these best practices is a great way to improve inbox placement, but this improvement rarely happens overnight. It’s a good idea to allow a few weeks for improvement after each round of changes.

If you have questions about Gmail deliverability or are having specific issues, please contact WhatCounts Support for further assistance.

Brad Gurley
Director of Deliverability, WhatCounts


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