Unfortunately there isn't a quick fix, Gmail is scanning and categorizing these emails for you. Using an email marketing software can be enough to be sorted into the Promotions tab according to this post: https://www.saleshandy.com/blog/avoid-gmail-promotions-tab/
There are two actions which your subscribers can take which are considered impactful on this categorization. Try to encourage your subscribers to:
Add your company's from email address to their address book in Google
Manually drag and drop emails into the Primary tab
Chances of your email reaching to the recipients primary inbox, instead of getting stuck in the promotions or spam filter are more if they have high rates of positive engagements. Engagements such as clicks and opens.
To improve the deliverability, the most important thing is creating quality content. In HubSpot,
Test your email before sending it to the contacts. Check you email in email optimizer and review recommendations. Also, ensure that your email is optimized for mobile devices.
In HubSpot, following are the email features that improve deliverability:
Connect your email sending domain.
Click Setting button in the main navigation bar.
Navigate to Website > Domains and URLs from the left-side menu bar.
Under Domain tab, scroll down to Email sending domains (DKIM) and connect an email sending domain.
Enable double opt-in on your HubSpot forms. With this feature on ,whenever a contact will submit a form, it will receive a follow-up email with a link to confirm their subscription. This helps you avoid fake or misspelled email addresses and ensures that all new contacts added to your database are actively engaged with your content.
To enable opt-in option:
Click Setting button in the main navigation bar.
Navigate to Marketing > Email from the left-side menu bar.
Under Subscriptions tab, scroll down to the end and witch the toggle Enable double opt-in.
Enable graymail suppression in your email settings. Graymails are those emails that sit unopened in your recipients' inbox, which makes you look like a spammy sender. This feature uses the Send since last property of teh contacts. It means the number of marketing emails that have been sent since the last engagement, specifically email open or link click.
To manage graymail suppression for a specific email:
Navigate to Marketing > Email.
Edit an existing email or create a new email.
Under Send or schedule tab, you will see a checkbox Don’t send to unengaged contacts. Click the checkbox to enable it.
Clicking unengaged contacts will show you the complete list of contacts that will exclude from the email list.
Also we recommend you to send a few email campaigns in HubSpot before enabling the graymail suppression feature.
Chances of your email reaching to the recipients primary inbox, instead of getting stuck in the promotions or spam filter are more if they have high rates of positive engagements. Engagements such as clicks and opens.
To improve the deliverability, the most important thing is creating quality content. In HubSpot,
Test your email before sending it to the contacts. Check you email in email optimizer and review recommendations. Also, ensure that your email is optimized for mobile devices.
In HubSpot, following are the email features that improve deliverability:
Connect your email sending domain.
Click Setting button in the main navigation bar.
Navigate to Website > Domains and URLs from the left-side menu bar.
Under Domain tab, scroll down to Email sending domains (DKIM) and connect an email sending domain.
Enable double opt-in on your HubSpot forms. With this feature on ,whenever a contact will submit a form, it will receive a follow-up email with a link to confirm their subscription. This helps you avoid fake or misspelled email addresses and ensures that all new contacts added to your database are actively engaged with your content.
To enable opt-in option:
Click Setting button in the main navigation bar.
Navigate to Marketing > Email from the left-side menu bar.
Under Subscriptions tab, scroll down to the end and witch the toggle Enable double opt-in.
Enable graymail suppression in your email settings. Graymails are those emails that sit unopened in your recipients' inbox, which makes you look like a spammy sender. This feature uses the Send since last property of teh contacts. It means the number of marketing emails that have been sent since the last engagement, specifically email open or link click.
To manage graymail suppression for a specific email:
Navigate to Marketing > Email.
Edit an existing email or create a new email.
Under Send or schedule tab, you will see a checkbox Don’t send to unengaged contacts. Click the checkbox to enable it.
Clicking unengaged contacts will show you the complete list of contacts that will exclude from the email list.
Also we recommend you to send a few email campaigns in HubSpot before enabling the graymail suppression feature.
Unfortunately there isn't a quick fix, Gmail is scanning and categorizing these emails for you. Using an email marketing software can be enough to be sorted into the Promotions tab according to this post: https://www.saleshandy.com/blog/avoid-gmail-promotions-tab/
There are two actions which your subscribers can take which are considered impactful on this categorization. Try to encourage your subscribers to:
Add your company's from email address to their address book in Google
Manually drag and drop emails into the Primary tab