Why cleaning before import matters
An import is the moment a platform decides whether to trust your account. A list full of dead addresses produces bounces on the first send, people who forgot you produce spam complaints, and both hit your sending reputation on the new platform before you have any history there.
Google's sender guidelines set the bar mailbox providers use: keep spam rates reported in Postmaster Tools below 0.10% and avoid ever reaching 0.30% or higher. [1] They also tell senders to automatically unsubscribe recipients who have multiple bounced messages and to consider unsubscribing people who do not open or read messages. [1] A clean import is how you start inside those numbers.
Purchased lists: the hard no
Google's guidelines say plainly: do not purchase email addresses from other companies, do not send messages to people who did not sign up, and make sure recipients opt in. [1] Kit says each person on your list is required to have given permission to receive your marketing emails, and that if you are not certain you have permission you may not contact that list via Kit or any other compliant provider. [2]
beehiiv makes you confirm before an import starts that everyone you are importing knowingly consented and opted in, and warns that importing contacts who did not opt in violates its terms and privacy policy and can lead to termination of service. [5] A bought or scraped list puts the whole account at risk, not just one campaign.
What each platform documents about imports
| Platform | File and format | Duplicates and existing data | Bad or inactive addresses |
|---|---|---|---|
| Kit | CSV only; .txt and .xlsx cannot be parsed [3] | Imported data replaces existing data, including blanks; existing tags are kept [4] | A row with no email stops the import from that point [3] |
| beehiiv | CSV; email header must be email, email address or emailaddress [5] | Overwrite of custom fields is on by default; blanks delete values; tags are not overwritten [5] | Duplicate, invalid and inactive emails are filtered and listed as Rejected [5] |
| MailerLite (API) | Statuses active, unsubscribed, unconfirmed, bounced, junk [6] | Upsert is non-destructive; omitted fields are kept [6] | Unsubscribed, bounced or junk cannot be reactivated [6] |
The spreadsheet cleaning routine
Work on a copy of the export, never the original. Each step below takes minutes in Google Sheets or Excel and removes a specific failure.
- Keep one email column with a plain header such as email; beehiiv requires the header to be email, email address or emailaddress. [5]
- Delete rows with a blank email; in Kit a missing address stops the import from that row onward, and on the first row fails the whole file. [3]
- Trim spaces and lowercase every address (TRIM and LOWER), then remove duplicates on that cleaned column.
- When duplicates disagree, decide which row's name and fields to keep before import; Kit will overwrite with whatever the file says. [4]
- Move unsubscribed, bounced and complained contacts to a separate suppression file and import them with that status, not as active. [6]
- Flag obvious typos in domains (gmial.com, hotmail.con) and fix only when certain; otherwise remove.
- Review role addresses (info@, admin@, sales@, support@) and keep only those with a clear signup record.
- Remove contacts with no signup source or date that you cannot vouch for. [2]
- Replace unusual characters that may break parsing; Kit names characters such as ç, θ and Þ as possible import problems. [3]
- Save as CSV (UTF-8) and record the final row count.
Worked example: a 4,200-row export
Say you export 4,200 rows from an old platform. Trimming and lowercasing reveals 140 duplicates, leaving 4,060. The status column shows 380 unsubscribed and 95 bounced; those go to the suppression file, leaving 3,585. Forty role addresses came from a trade-show badge scan with no opt-in, so they go too, leaving 3,545 active contacts to import plus 475 suppressed records.
That is the number to compare with the new platform's plan limits and with the import report afterwards. If beehiiv shows rows under Rejected, compare them against your file before assuming the platform is wrong. [5]
| Step | Rows removed or moved | Rows left |
|---|---|---|
| Raw export | 4,200 | |
| Duplicates after trim and lowercase | 140 removed | 4,060 |
| Unsubscribed and bounced | 475 moved to suppression | 3,585 |
| No-consent role addresses | 40 removed | 3,545 |
After the import
- Compare the platform's imported count with your row count, and read every rejected row.
- Pause automations before importing; Kit says tagged or form-based imports may trigger Visual Automations and sequences. [4]
- Send the first campaign to your most engaged segment, then widen it.
- Watch bounce and complaint numbers for two weeks; Google advises reducing volume if bounces or deferrals rise. [1]
- Keep the cleaned file and the suppression file with the date of import.
Questions before you decide
Will the platform remove duplicates and bad addresses for me?
Partly. beehiiv says it automatically filters out duplicate, invalid and inactive emails and lists them as Rejected. Kit's import treats an existing address as an update and replaces stored data, including with blank cells. Cleaning first keeps you in control of which version wins.
Should I delete role addresses like info@ or sales@?
Not automatically. Review them: keep a role address if a person there clearly signed up, and remove it if it was scraped from a website or added without a signup. We did not find a documented rule in Kit, beehiiv or MailerLite that rejects role addresses outright, so this is a judgment call about consent.
Can I re-activate people who unsubscribed by importing them again?
You should not. MailerLite's API says subscribers with an unsubscribed, bounced or junk status cannot be reactivated through its update call due to abuse-prevention measures, and Google's guidelines tell senders not to message people who did not sign up. Only re-add someone who has opted in again.
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- Google: Email sender guidelines Accessed 29 Oct 2026
- Kit Help: Importing subscribers into Kit, what to know (FAQs) Accessed 29 Oct 2026
- Kit Help: Troubleshooting importing subscribers (pre-import) Accessed 29 Oct 2026
- Kit Help: How to import a subscriber list Accessed 29 Oct 2026
- beehiiv Support: How to import free subscribers and map custom fields or tags Accessed 29 Oct 2026
- MailerLite API documentation: Subscribers Accessed 29 Oct 2026
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