Email deliverability

Email deliverability is the ability of your emails to reach users’ inboxes instead of being marked as spam or blocked. High deliverability is vital for user engagement.

This post outlines key email deliverability best practices and explains how Pushwoosh supports them with real-time validation, bounce management, double opt-in, and sunset flow automation.

To maintain high deliverability and protect your sender reputation, follow these universal best practices:

• Remove invalid, inactive, or misspelled addresses (e.g., @gnail.com).

• Eliminate disposable or temporary emails.

Double opt-in is a two-step process for collecting email consent. After a user submits their email address (e.g., via a form or app registration), they receive a confirmation email with a link. Only after clicking this link is the user added to your mailing list.

Why it is important

• Improves deliverability by ensuring only real, interested users are subscribed

• Reduces spam complaints and protects sender reputation

• Increases engagement quality by filtering out fake or low-intent signups

• Supports legal compliance with data protection and anti-spam regulations

Track how your audience interacts with your emails to spot and fix potential deliverability issues early. Focus on key metrics like opens, clicks, bounces, and spam complaints. Learn more

To prevent your emails from being flagged as spam:

• Avoid excessive use of promotional language (e.g., “Buy now!”, “Free!” in subject lines)
• Do not use deceptive subject lines or misleading headers
• Limit the use of all caps and multiple exclamation points
• Keep a healthy text-to-image ratio
• Ensure that the content is relevant and expected by the recipient

• Do not purchase email lists.

• Avoid sudden spikes in sending volume.

• Use consistent sender names and addresses.

Users who don’t engage with your emails, even if their addresses are valid, can still hurt your deliverability. To keep your list healthy, identify inactive users and ask them to confirm whether they still want to receive your emails. This process is called a sunset email flow.

A sunset flow helps you:

• Clean your list by removing users who no longer engage
• Improve open and click rates
• Lower the chance of being marked as spam
• Protect your sender reputation

Pushwoosh includes several built-in mechanisms to automatically protect your email reputation and keep your list clean.

When users register their email addresses, Pushwoosh automatically blocks malformed entries (e.g., missing “@” or domain) and rejects disposable or temporary email addresses. This validation helps reduce bounces, avoid wasted sends, and protect your sender reputation.

Pushwoosh automatically checks email addresses against its internal bounce list and blocks re-registration of addresses marked as bounced. This helps maintain a clean email list and protects your campaign performance.

How it works

1. Pushwoosh monitors every email delivery attempt.
2. If a message bounces, the system captures the response and classifies it as a hard or soft bounce.
3. In case of a hard bounce, the email address is added to an internal “bounced list” and excluded from your subscriber list.
4. If a user later tries to register with an email address already on the bounced list, Pushwoosh will automatically prevent it from being added to your email audience, maintaining the integrity of your contact list.

Pushwoosh enables you to create automated double opt-in flows using Customer Journey. This helps you verify new subscribers’ intent and maintain list quality.

Pushwoosh also supports automated sunset email flows to identify disengaged users and prompt them to confirm their interest. This ensures your list remains active and reduces the risk of spam complaints.

To provide a seamless opt-out experience, Pushwoosh supports the List-Unsubscribe header in emails. When enabled, this header allows mailbox providers like Gmail and Yahoo to display a native Unsubscribe button directly in the email inbox interface, making it easier for recipients to opt out without searching for a link in the message body.

Using the List-Unsubscribe header helps improve deliverability by reducing spam complaints, meeting mailbox provider requirements, and protecting your sender reputation.

How to use

Pushwoosh automatically includes a default unsubscribe link in the List-Unsubscribe header for all emails.

To customize unsubscribe behavior, for example, to let users unsubscribe from a specific category, you can create your own unsubscribe form and logic. Then, include the link to that form as a custom unsubscribe URL by passing it in the list_unsubscribe parameter when sending emails via the createEmailMessage API. This URL will be added to the List-Unsubscribe header.