When you import a list into MailChimp we'll scan your file for duplicates, bounces, and unsubscribes. It the system comes across an incorrect file format, an incomplete or malformed email address, or inconsistencies in the file, all or some of the email addresses may be blocked form import. Below we'll walk through some issues that could cause the import to fail.
If you're importing a large list, it can take some time to complete the upload. If you navigate away from the import area, you can go back to the Lists page to see if your import is still processing. We'll display a notice if the import has not been completed. We'll also notify you once your import is complete by showing a message at the top of any page in your account.
Check the file type
If you chose the Upload from File option, make sure the file you are using is a tab-delimited text file or CSV file. The system is not designed to support imports of Excel (.xls), ACT!, .vcf (vCard), or other file types.
Spaces in the file
Make sure the email addresses don't contain beginning or trailing spaces. Some export utilities sometimes add invisible spaces in the middle of email addresses too. Extra spaces can result in an otherwise-valid address being reported as a syntax error. If you do have spaces, the TRIM function in Excel can remove all spaces from text (except for single spaces between words). Consult the help documents for your version of Excel to learn how to use the TRIM function. Other spreadsheet programs may have similar functions as well.
Typos in the address
Check the file to see if there's a typo in the email address. We check for misspellings of common domains, such as gamil.com instead of gmail.com and prevent them from being added to your list. This helps keep your list free of bounces.
Check the OPTIN_TIME or CONFIRM_TIME
Importing an OPTIN_TIME or CONFIRM_TIME with a future date will cause a syntax error. Additionally, our system only looks at these fields the first time you import the subscriber. We won't change the times or check that field when a subscriber is being updated.
If you are switching from another ESP, the file that was exported may not be formatted in a way that MailChimp can read. Take a look at this article for info on how to format your import file. In addition, if you're switching over from Constant Contact and have more than 60 lists, you may see an error on the import. There is a limit to the number of lists that can be converted to Groups in MailChimp.
You can visit the List Import History page for a full breakdown of the results. The upload details will be available to view in the account for about 24 hours.
If the numbers shown on the Import History page don't add up based on your total subscriber count, there are a few things to look for.
Was the Auto-Update My Existing List option enabled?
We'll add any new email addresses to your list as new subscribers. If an email address is already on your list, instead of completely skipping it as a duplicate, we'll check all the fields and update that subscriber's information. Updated subscribers won't increase your list size, but will be included in the number of emails added or updated. You can tell whether this option was enabled because the import results will display that email addresses were added or updated instead of just added.
Was an account upgrade triggered during the import?
If you reach the upper limit of your current monthly plan with an imported list, the import process will stop temporarily and trigger an account upgrade confirmation email. This email is sent to the contact address listed under Account > Contact Information > Administrator. Here's what your list import will look like while awaiting an upgrade:
Once the upgrade is confirmed, the import will generally restart: