Deliverability Best Practices

Email messages from any source have the potential to be filtered by their recipients. Almost anyone who receives emails is using some spam filter.

Spam filtering is a complex topic. Many mail services use various technologies to detect and filter spam and data from several sources to inform their filtering. Because of this, Mixmax, like any other service, cannot guarantee that your messages will not be filtered. But there are steps you can take to maximize the chance that your messages are received and opened by your recipients.

Settings for custom domains

If you use Google Workspace and have your custom email domain, you should ensure that standard email security settings are configured for your domain. You should also ensure you can get information about your domain’s email reputation. These are partially or entirely external settings to Mixmax, outlined in the sections below. It would be best to ensure these are in place before sending Mixmax messages or sequences.


SPF, DKIM, and DMARC are tools for authenticating email messages. They ensure that email messages are sent from an authorized server and have a digital signature that validates the sending server. Having these in place ensures your recipients that your domain is sending these messages and will make anything you send significantly less likely to be filtered as spam.

You can check the Email Diagnostic page in the Mixmax dashboard to see if SPF, DKIM, and DMARC have already been configured for your domain. If they have not been, you should work with your IT team, DNS administrator, or hosting provider to add the appropriate DNS records and Google Workspace settings.

It is important to note that SPF, DKIM, and DMARC are maintained by you or your hosting provider, not Mixmax, and cannot be modified through Mixmax. You will need help from your IT team to ensure these are configured correctly.

You can find additional information about the tools and how to set them up for your Google Workspace domain in these articles:

SPF records specify which mail servers are permitted to send emails on behalf of your email domain. It prevents spammers from sending emails that pretend to be from your domain. If your SPF records are not set up correctly, your emails may not be accepted by your recipient's mail server (resulting in a bounceback email) or get caught in your recipient's spam filters.

Ensure mail delivery & prevent spoofing (SPF)

DKIM is a digital signature that you can add to your outgoing mail. It encrypts your email header and enables email servers that receive your message to verify that it is coming from your email domain.

Enhance security for outgoing email (DKIM)

DMARC is a protocol that uses SPF and SKIM to determine whether an email message is authentic. Adding a DMARC record will improve the deliverability of your email.

Enhance security for forged spam (DMARC)

Custom Domains in Mixmax 

Mixmax allows you to use your custom domain for Mixmax open, link tracking, and Calendar links. Using a custom domain for tracking ensures that you send links that look like they come from you directly. It improves your deliverability in two ways:

  • Messages with links to the same domain as the sender help affirm your identity and are less likely to be filtered.
  • Messages with links to your domain will not appear similar to messages sent by other Mixmax users, which prevents your messages from being associated with other senders.

Setting up custom domains requires additional DNS entries to be configured in your domain, and you may need assistance from your IT team, DNS administrator, or hosting provider. See our document Custom Domains For Tracking And Calendars for the necessary steps.

Google Postmaster Tools

Google’s Postmaster Tools allow you to see additional data about your domain’s email traffic, reputation, and spam rates. We recommend configuring this service for your domain. If you send only a tiny amount of traffic, these statistics may not be available initially, but setting the service up will allow you to see once you have sent a sufficient volume of emails. You should monitor these statistics and consider changing your outbound email strategy if you start to see negative changes. In particular, if you see a User Reported Spam Rate above 0.5%, you should make changes to your email content. Users manually reporting spam at that rate will significantly affect your deliverability.

See Google’s document Getting Started With Postmaster Tools to learn more about setting this up.

Settings for all users

These settings are internal to Mixmax and apply whether you have a email address or have your custom email domain.

Daily Send Limits

The Daily Send Limit feature limits the number of sequence messages users in your workspace can send daily. Recipients treat senders who send large amounts of email over short periods as more likely to be spammers. Limiting your daily sequence message volume will help to prevent this. Consider setting your Daily Send Limit to 300 or less, especially if your domain does not have a history of sending large amounts of emails. See our Daily Send Limit article for information on how to configure this.

Unsubscribe Links

Unsubscribe links allow your recipients to tell you they don’t want to hear from you anymore. Once they click the unsubscribe link, they will automatically be removed from any active sequences and cannot be added to future sequences. Including an unsubscribe link is a best practice because it is polite to your recipients and because spam filters consider automated messages sent without unsubscribe links more likely to be spam. 

You should configure your roles in Mixmax to have unsubscribe links in sequence messages. See our article Add an ‘Unsubscribe’ Link To Your Sequences for details.

General Best Practices

These are additional steps you can take to improve your messages' deliverability.

  • Keep your message sending volume consistent. Sudden increases in message volume can be seen as a sign of spamming. If you need to increase your sending volume, ramp it up slowly.
  • Make sure your messages don't look automated. Use sequence variables to personalize messages and keep the text similar to a hand-written letter. If your message reads like it was sent automatically, spam filters are more likely to treat it as spam.
  • Avoid terms and phrases that suggest your message is an attempt to sell a product, conduct a contest, or other explicitly commercial purposes. These messages are more likely to be filtered and more likely to be manually marked as spam by recipients.
  • Limit the use of HTML, images, and links. Large amounts of these in a message will trigger some filters.
  • Relatedly, consider disabling tracking if deliverability is your primary concern. Open, click, and download tracking all rely on images or links in your message to function and can slightly increase the chance your message is filtered.
  • Send messages to known good email addresses, ideally those you have collected from interested recipients. Messages which bounce and are marked as spam by recipients hurt your email reputation and increase the likelihood of future messages being filtered.
  • Avoid purchasing email lists. Large commercial lists often contain bad and unused addresses. Sending to them can hurt your domain's reputation.
  • If your sequence metrics start decreasing, you should change your sequence content. Mail systems treat messages with identical text to previous messages as more likely to be spam. Additionally, if recipients mark a message as spam, future similar messages will likely be filtered automatically. Changing your content can avoid this.

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