What are the best practices for importing email contacts and what fields are required?
Matthew Whittaker
Co-founder & CTO, Suped
Published 28 Jul 2025
Updated 15 Aug 2025
6 min read
Importing email contacts might seem like a straightforward task, but it is a critical step that can significantly impact your email deliverability and overall sender reputation. Many email marketers simply upload a CSV file and expect all emails to land in the inbox, only to be surprised by high bounce rates or low engagement.
The reality is, a poorly managed contact import can lead to serious consequences. Sending emails to invalid addresses, spam traps, or recipients who haven't given their consent can quickly get your domain or IP address listed on email blocklists (also known as blacklists). Once you are on a blocklist, it becomes incredibly difficult to reach your audience, impacting your marketing efforts and business operations.
To ensure your emails reach the inbox, it's essential to follow a set of best practices for importing contacts. This includes understanding which fields are truly required, how to prepare your data for a clean import, and the crucial role of consent in maintaining a healthy sending environment.
Required fields for a healthy import
When importing email contacts, the most fundamental and universally required field is the email address itself. Without a valid email address, there is no recipient for your messages. This field serves as the unique identifier for each contact within your email marketing platform or CRM.
While the email address is the only strict technical requirement for sending, several other fields are highly recommended for effective and compliant email marketing. These include the contact's first name, last name, and crucially, their consent status. Having names allows for personalized communication, which significantly improves engagement rates.
The specific set of required fields can sometimes vary depending on the email service provider (Mailchimp) or CRM you are using. For instance, some platforms might require at least a last name in addition to the email. Always consult your platform’s documentation for their precise import requirements.
Field
Requirement
Purpose
Email Address
Required
Primary identifier for sending communications
First Name
Recommended
Enables personalization and better engagement
Last Name
Recommended
Additional personalization and identification
Consent Status
Critical for compliance
Legal proof of opt-in, crucial for deliverability and avoiding blocklists
Source
Recommended
Tracks where the contact originated, aids segmentation
Best practices for data hygiene before import
A crucial step often overlooked is cleaning your contact list before you import it. Importing a dirty list, even with seemingly valid email addresses, can severely damage your sender reputation. Dirty data includes duplicates, invalid formats, or email addresses that are known to be hard bounces.
Start by removing duplicate entries and ensuring all email addresses conform to a valid format. Many platforms, like Mailchimp, provide guidelines on how to format your import file correctly. Additionally, it's wise to cleanse out any email addresses that have previously resulted in hard bounces, as these are permanently undeliverable.
Employing an email validation service before importing is one of the most effective ways to ensure list hygiene. These services identify invalid, risky (including spam traps), and non-existent email addresses, drastically reducing your bounce rate and preventing your domain from landing on a blocklist.
Pre-import checklist
Data cleanliness: Remove duplicate entries, invalid email formats, and known hard bounces. Many providers like HubSpot emphasize this.
Consent verification: Ensure every contact has explicitly opted into receiving emails.
Field mapping: Match your CSV columns to the appropriate fields in your email platform.
UTF-8 encoding: Save your CSV file with UTF-8 encoding to avoid character display issues.
Small batches: For very large lists, consider importing in smaller batches to monitor performance.
Consent and compliance considerations
Beyond technical formatting, the most critical aspect of importing contacts is obtaining and managing explicit consent. Sending emails to individuals who have not opted in can severely damage your sender reputation, lead to high spam complaints, and even result in legal penalties under regulations like GDPR or CAN-SPAM.
Simply possessing an email address is not sufficient justification for sending marketing communications. You need clear, verifiable proof that each recipient has given their permission. This is why including a consent status field in your import file, along with the date and method of opt-in, is essential for compliance and good deliverability.
The repercussions of importing purchased lists, scraped data, or very old, unverified contacts are significant. Such lists often contain a high percentage of invalid addresses and spam traps, which can quickly lead to your domain or IP address being added to an email blocklist (or blacklist). It's crucial to understand these risks, as highlighted in import overviews from providers like Constant Contact.
Compliant imports
Compliant email lists are meticulously built through transparent and often double opt-in processes, ensuring every subscriber genuinely wants to receive your emails.
Explicit consent: Each subscriber actively agreed to receive emails from your brand.
Record of consent: The timestamp and method of subscription are meticulously recorded.
Regular cleaning: Inactive subscribers and hard bounces are routinely removed from the list.
Non-compliant imports
Non-compliant email lists are typically sourced from third-party vendors or comprise old, unverified data, often leading to poor deliverability.
Lack of consent: Subscribers have not explicitly opted in, making these emails unsolicited.
High risk: Frequently results in increased spam complaints and blocklisting (or blacklisting).
Legal issues: Potential for significant fines and legal action under privacy regulations.
Managing imports and long-term list health
For new and particularly large email imports, especially those from older or less reliable sources, consider a gradual approach to sending. Many reputable email service providers will recommend (or even enforce) a warming-up period or use sandbox environments for new senders. This allows them to monitor your initial sending metrics and ensure your practices align with deliverability standards before granting full sending privileges.
Maintaining ongoing list hygiene is equally important after the initial import. This means actively suppressing unsubscribes, hard bounces, and complaints as they occur. Regularly validating your list helps you avoid hitting spam traps and maintain a strong sender reputation over time.
Effective bounce management is a cornerstone of good deliverability. While checking for dead domains before import can give you an early indication of list quality, your ESP’s automated bounce handling system will diligently remove non-existent or problematic addresses post-send, protecting your sender score.
Example CSV structure for contact importcsv
Email,FirstName,LastName,ConsentStatus,SignupDate,Source
john.doe@example.com,John,Doe,Opted-In,2023-01-15,Website Form
jane.smith@example.com,Jane,Smith,Opted-In,2023-02-20,Webinar
sally.jones@example.com,Sally,Jones,Opted-In,2023-03-10,Direct Mail
Views from the trenches
Best practices
Always ensure explicit consent has been obtained for every contact on your import list before sending.
Utilize an email validation service to pre-clean your list, identifying invalid or risky email addresses.
When migrating from another ESP, request a complete export that includes all suppression flags like unsubscribes and hard bounces.
For large or questionable lists, consider a gradual import process with monitored metrics.
Implement internal policies to educate users on email deliverability best practices and the consequences of poor list hygiene.
Common pitfalls
Importing lists without verifying consent or data quality, leading to high bounce and complaint rates.
Believing that removing only dead domains is sufficient for list hygiene, instead of comprehensive validation.
Ignoring the friction between sales targets and deliverability best practices, which can compromise sender reputation.
Failing to export and import suppression data (unsubscribes, bounces) when moving between email service providers.
Not leveraging initial sending limits or sandbox environments to assess new list quality before full deployment.
Expert tips
Beyond just the email, consider including fields like consent history and preferred language for better segmentation.
Use data quality metrics, such as the percentage of dead domains, as an indicator of overall list health.
Develop a suspicious filter to automatically alert users and block uploads containing known typos or problematic domains.
Establish clear dashboards with key deliverability indicators to align customer practices with platform health.
Incentivize long-term viable customer relationships by linking sales commissions to sustained positive deliverability metrics.
Marketer view
Marketer from Email Geeks says the email address is the only mandatory field for import. Consent is already covered by the client's contract, so it doesn't need to be explicitly in the data. If you allow non-consenting email addresses, it's a risky practice and requires a solid audit trail or a 'never mail this' flag.
2021-04-10 - Email Geeks
Marketer view
Marketer from Email Geeks says they always ask for the list's origin and if the client can certify that every recipient has given consent. They also recommend running the list through a reputable email verification service before sending.
2021-05-22 - Email Geeks
Maintaining a healthy email list
Ultimately, successful email marketing campaigns begin with a commitment to clean, consented, and well-managed contact lists. By adhering to best practices for importing, focusing on data hygiene, understanding the legalities of consent, and continuously maintaining your list, you can significantly improve your email deliverability rates. This proactive approach not only ensures your messages reach their intended recipients but also safeguards your sender reputation, preventing costly issues like blocklisting (or blacklisting) and ensuring the long-term success of your email program.
Mailchimp) or CRM you are using. For instance, some platforms might require at least a last name in addition to the email. Always consult your platform’s documentation for their precise import requirements.
HubSpot emphasize this.
