Emails can easily get lost in spam folders. So, it's critical to ensure that your message stands out and bypasses spam filters.
Spam filtering is a complex topic. Many mail services use various technologies to detect and filter spam, drawing on 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 you can take steps to maximize the chance your messages are received and opened, and Mixmax will help you reach that goal!
Google email sender guidelines
Gmail requires that senders who send 5,000 or more messages a day to Gmail accounts meet the requirements outlined in Gmail guidelines for email senders. Even if you send fewer emails a day but expect that number to increase at some point, take proactive measures to ensure your emails aren't flagged as spam.
Below are some best practices for protecting your email reputation that Mixmax recommends. You will also learn what settings you can configure in Mixmax and outside of it to optimize email deliverability and become compliant with Gmail regulations.
Settings for custom domains
If you use Google Workspace and have a custom email domain, ensure you configure standard email security settings for your domain. You should also make sure you can get information about your domain's email reputation.
In the sections below, you will find settings that are partially or entirely external to Mixmax. We strongly recommend setting them up before sending Mixmax messages or sequences.
SPF, DKIM, and DMARC
SPF, DKIM, and DMARC are tools for authenticating email messages. They ensure email messages come from an authorized server and include a digital signature that validates the sending server. Having these in place assures recipients that your domain is sending the messages and makes anything you send significantly less likely to be filtered as spam.
Each time you activate a sequence, Mixmax checks your sending domain for SPF, DKIM, and DMARC. If a record is missing or can't be confirmed, a warning appears before your sequence starts sending, showing each record's status.
From the warning, you can:
Forward setup instructions to IT: Send your IT team a pre-written email with the setup steps, right from Mixmax.
Set up now: Open setup instructions for the records that need attention.
Verify: If DKIM shows as Not detected, confirm your DKIM setup with a test email. See Verify your DKIM setup below.
Activate anyway: Start sending your sequence without changing anything.
To stop seeing the warning for your domain, check Don't warn me again and click Activate anyway. This only applies to you. Teammates who send from the same domain will still see the warning.
You can also check the Email Diagnostic page in the Mixmax dashboard to see if SPF, DKIM, and DMARC have already been configured for your domain.
If your records aren't set up, work with your IT team, DNS administrator, or hosting provider to add the appropriate DNS records and Google Workspace settings.
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 these tools and how to set them up for your Google Workspace domain in the articles linked below:
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.
DKIM is a digital signature that you can add to your outgoing mail. It encrypts your email header and lets receiving email servers verify that it comes from your email domain.
DMARC is a protocol that uses SPF and DKIM to determine whether an email message is authentic. Adding a DMARC record will improve your email deliverability.
Just added your records? DNS changes can take up to 24 hours to take effect, so the sequence check may still report records as missing right after your IT team adds them. If you have already used Forward setup instructions to IT or Set up now, you will see a shorter reminder instead of the full warning for the next 48 hours. Once your records are live, you won't need to reconfigure anything in Mixmax, as the warning message will disappear.
Verify your DKIM setup
Mixmax looks for your DKIM key in your domain's DNS records. Some domains store the key under a custom name (called a selector) that Mixmax can't find this way. When that happens, the warning shows DKIM as Not detected and adds a Verify button next to it.
When you click Verify, Mixmax sends one test email from your account to Mixmax and checks its DKIM signature. This usually takes a few seconds.
If the signature is valid, you'll see a confirmation and can activate your sequence. The result applies to everyone who sends from your domain, so your teammates won't need to verify it again.
If the test email doesn't have a DKIM signature for your domain, DKIM shows as Missing. Click Check in Google Admin to turn on DKIM for your domain, or forward the setup instructions to your IT team. Once DKIM is turned on, click Check again.
The test email is a real message sent from your account, so you'll see it in your Sent folder with the subject Mixmax email authentication check. You can run up to 3 checks per hour, and one check per domain every 15 minutes.
Custom Domains in Mixmax
Mixmax lets you use your custom domain for Mixmax open and link tracking, as well as Calendar links. Using a custom domain for tracking ensures your links look like they come directly from you. 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 won't look like messages sent by other Mixmax users, which helps keep your messages from being associated with other senders.
Setting up custom domains requires additional DNS entries, and you may need help from your IT team, DNS administrator, or hosting provider. See our article 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 up the service will let you see them once you send enough emails.
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 0.3%, you should change your email content. Users manually reporting spam at that rate will significantly affect your deliverability.
See Google's article Getting Started with Postmaster Tools to learn more about setting this up.
Microsoft 365 email authentication standards
Outlook-based users can improve email deliverability by following Microsoft 365 standards, also known as email authentication or validation.
Email authentication protocols help you shield against phishing and ensure your emails land securely in recipients' inboxes, while avoiding spam filters.
To learn more about email authentication in Microsoft 365, see this Microsoft support article.
Settings for all users
These settings are internal to Mixmax and apply whether you have a gmail.com email address or have your custom email domain.
Daily Send Limits
The Mixmax 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. For new users, we recommend starting with a daily send limit of 100–200 emails per user during the first week and gradually increasing this limit over time to build your domain reputation. Additionally, Mixmax enforces a hard cap of 1,000 automated sequence emails per day to align with Gmail/Google Workspace restrictions and protect your domain reputation. You can view your current Daily Send Limit directly in the Mixmax sequence interface when adding recipients. Regularly checking this limit helps you plan your email campaigns effectively.
Unsubscribe links
Unsubscribe links let recipients tell you they no longer want to hear from you. Once they click the unsubscribe link, they will be automatically removed from any active Mixmax 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
We never recommend using Mixmax for blast marketing. By taking a more targeted approach and personalizing sequence emails, you can reduce the risk of emails being marked as spam and help ensure your messages are delivered successfully.
These are the additional steps you can take to improve your messages' deliverability:
Personalization
Make sure your messages don't look automated. Use Mixmax Sequence variables to personalize messages and compose them like a handwritten 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 for other explicitly commercial purposes. These messages are more likely to be filtered and manually marked as spam by recipients.
Use Mixmax AI Compose to fine-tune your existing email drafts and craft new personalized emails from prompts.
Access Salesforce or LinkedIn Sales Navigator data directly from your Gmail Inbox through the Mixmax Sidebar, and use Mixmax Email Templates for a more efficient personalization workflow.
Consistency
Keep your message-sending volume consistent. Sudden increases in message volume can look like spamming. If you need to increase your sending volume, ramp it up slowly.
Deliverability
Limit HTML, images, and links usage. 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 relies on images or links in your message, which can slightly increase the chance your message is filtered.
Include unsubscribe links in your sequences so recipients can opt out of further communication. Use Mixmax Rules and Salesforce integration to automatically update the Lead/Contact Opt-out status in your CRM.
Diversity
Include Call, SMS, and LinkedIn tasks as your Mixmax sequence stages for multi-channel outreach. Avoid using only emails for prospecting.
Add manual email stages to Mixmax sequences to deliberately interrupt the automated message chain and add more personal input.
If your sequence metrics start to decline, 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, similar future messages will likely be filtered automatically. Changing your content can help to avoid this.
Reputation
Send messages to known good email addresses, ideally, those you have collected from interested recipients. Bounced messages and spam reports hurt your email reputation and make it more likely future messages will be filtered.
Avoid purchasing email lists. Large commercial lists often contain bad and unused addresses. Sending to them can hurt your domain's reputation.
Consider setting up BIMI. Brand Indicators for Message Identification (BIMI) enhances email security and brand recognition by allowing your logo to appear next to authenticated emails. This reduces phishing risk and can increase engagement through visual trust cues. Click here to learn more.
FAQ
Do I have to fix my records before I can activate a sequence?
No. The warning never blocks your sequence. Click Activate anyway to start sending right away. We still recommend setting up SPF, DKIM, and DMARC as soon as you can, since emails from domains without these records are more likely to land in spam.
Which domain does Mixmax check?
Mixmax checks the domain of the address that sends the first email stage of your sequence. If that stage sends from an email alias or on behalf of a teammate with delegated sending, Mixmax checks that address's domain.
Does the check run for every account?
The check runs for Google accounts on a domain you own. It doesn't run for:
Personal email addresses, such as gmail.com addresses, since you can't add DNS records to a domain you don't own.
Outlook accounts, including sequences sent on behalf of a teammate who uses Outlook. See Microsoft 365 email authentication standards above for Outlook guidance.
The Verify button is also not available for Outlook accounts or personal email addresses. If Mixmax can't complete the check, for example because of a temporary DNS error, your sequence activates normally without a warning.
Gmail shows DKIM: PASS, but Mixmax shows DKIM as Not detected. Why?
Gmail can show DKIM as passing even when your domain doesn't have its own DKIM key. To check, open an email you sent to a Gmail address, click the three dots, and select Show original (see Trace an email with its full headers). Then look at the domain next to the DKIM result:
If it's your own domain, DKIM is set up under a selector Mixmax can't find automatically. Click Verify in the warning to confirm it.
If it ends in gappssmtp.com, Google signed the email with its shared default key because DKIM isn't turned on for your domain. Turn it on in the Google Admin console under Apps > Google Workspace > Gmail > Authenticate email. See Google's article Enhance security for outgoing email (DKIM).
DKIM keys you've set up for other tools, such as Mailchimp or SendGrid, only cover emails those tools send. Mixmax sends through your Google account, so it needs the DKIM key for your Google Workspace domain.
What if DKIM verification takes longer than usual?
If the test email doesn't arrive right away, you'll see Still verifying your DKIM record. You can click Activate anyway to start your sequence now, or Check back later. Either way, Mixmax checks your records again the next time you activate a sequence.
I send from a subdomain. Do I need a separate DMARC record?
Not necessarily. If your subdomain doesn't have its own DMARC record, Mixmax uses the DMARC policy on your parent domain, which covers its subdomains. For example, if you send from mail.example.com, Mixmax checks the DMARC record for example.com.
Do I need to add any DNS records specifically for Mixmax?
No. For SPF, DKIM, and DMARC, you only need the standard records for your Google Workspace domain. Mixmax doesn't require any additional records. Custom domains for tracking and calendars are optional and use their own DNS records. See Custom Domains for Tracking and Calendars.
Can I run an email deliverability test?
Yes, in part. The Email Diagnostic page in your Mixmax dashboard checks whether SPF, DKIM, and DMARC are configured correctly for your domain — misconfigured authentication records are among the most common causes of poor deliverability. If it shows DKIM as not set up but you've turned DKIM on, your key may use a custom selector. Use Verify in the sequence activation warning to confirm it.
Mixmax does not offer an inbox-placement test — a seed-list test that shows whether your message lands in the inbox or the spam folder. To monitor your domain's reputation and spam rate over time, use Google Postmaster Tools (described above). For a one-off inbox-placement check, use a dedicated third-party deliverability testing tool.