# Email Deliverability Guide

Email deliverability refers to the ability of an email to successfully reach a recipient’s inbox, instead of being filtered into spam or rejected. The better deliverability a sender has, the more chance that their emails will stay out of the recipient’s spam folders.

Email delivery and email deliverability are often mistakenly used interchangeably, but they are two distinct concepts:

- **Email delivery** is the number of emails delivered to the recipient server, regardless of where emails go after that.
- **Email deliverability** focuses on what happens after delivery, measuring the ability to deliver an email to its intended placement in the recipient’s inbox.

Think of a package delivery service: a package addressed to your home could be marked as delivered, even if the package was left at your neighbor’s front door. Package deliverability would be poor in this case, as the package did not reach its intended address.

## Why is Email Deliverability Important?
As a business, understanding and monitoring your email deliverability is crucial as it directly influences the following:

1. **Customer engagement**: If your emails aren’t delivered to your customers' inboxes, you’re missing your opportunity to engage with your customers.
2. **Reputation management**: Your email domain can earn a poor reputation based on your deliverability rates, which can harm communication across your business. If you send too many emails that bounce or end up in spam, your domain will be flagged as an untrustworthy sender by email providers.
3. **Email campaign ROI**: When your team spends time reaching out to your customers via email, low deliverability means wasted effort and cost. Your audience can’t engage with your business if they don’t receive your emails.

## What Factors Impact Email Deliverability?
There are several factors that determine email deliverability, working together to influence whether your email successfully reaches its intended place in the inbox:

1. **Sender reputation**
2. **Email authentication**
3. **Email content hygiene**
4. **Recipient engagement and validity**

### Sender Reputation
Sender reputation is one of the most critical factors for email deliverability. Internet Service Providers (ISPs) track and score email senders based on their sending habits. If a large number of your sent email bounces, or if too many recipients mark your emails as spam, your sender reputation will be negatively impacted. A poor sender reputation means that emails you send from your domain or IP address carry a high risk of landing in the spam folder or being rejected.

**Best practices for maintaining a positive sender reputation:**  
- Warm up your sending domain gradually.  
- Regularly monitor your IP addresses to ensure they don’t appear on any blocklists.  
- Analyze and address email bounces promptly.  
- Sign up for feedback loops from providers such as Yahoo and Gmail.

**Recommended tools:**  
- [MXToolbox](https://mxtoolbox.com/emailhealth)  
- [Google Postmaster](https://gmail.com/postmaster/)  
- [Sender Score](https://senderscore.org/)

### Email Authentication
Email authentication is a framework of protocols used to prevent spoofing. The protocols authenticate your emails so that ISPs can trust that emails sent from your domain are genuinely coming from your company.

**Common authentication protocols:**  
1. **SPF (Sender Policy Framework)**  
2. **DKIM (DomainKeys Identified Mail)**  
3. **DMARC (Domain-based Message Authentication, Reporting & Conformance)**

### Email Content Hygiene
The content within your email can also significantly impact its deliverability. Here are some best practice guidelines:
- Send personalized and relevant content.  
- Avoid spammy keywords and phrases.  
- Use links sparingly.  
- Avoid sending attachments, especially large ones.  
- Maintain a healthy text-to-image ratio.  
- Ensure clean, simple code.

**Recommended tools to test email content:**  
- [MXToolbox](https://mxtoolbox.com/deliverability)  
- [Postmark](https://spamcheck.postmarkapp.com/)  
- [Mailtrap](https://mailtrap.io/email-spam-checker/)  
- [Litmus](https://www.litmus.com/)

### Recipient Engagement and Validity
ISPs track how recipients interact with your emails. Keeping your contact lists clean is one of the easiest ways to improve deliverability. Here are a few best practices:
- Verify the email addresses in your list.  
- Regularly clean your list by removing inactive or bounced email addresses.  
- Monitor spam complaint and unsubscribe rates.

**Recommended tools to check email validity:**  
- [Hunter.io](http://hunter.io/)  
- [Mailtester](https://mailtester.com/en/email-list-verify)

## Attio's Deliverability Protection Features
Sequences were intentionally designed with deliverability in mind. Attio has placed safeguards to help prevent your emails from being caught up in spam:

- Any email sent from a sequence that hard bounces will be automatically added to the **Unsubscribes** list.  
- Unsubscribe links are required on all emails sent through Sequences.  
- Attio uses email sending limits to space out email delivery.