MailChimp scans each list import file for duplicates, bounces, and unsubscribes, as well as errors. Incorrect file formats, incomplete or malformed email addresses, or other inconsistencies in the file, can cause some or all email addresses to be blocked from import. Below, you'll learn more about the issues that could cause problems with your import.
- Lists of more than a hundred thousand contacts can take some time to import. We'll send a confirmation message to the Primary Account Contact's email address, and post a notification in your Account drop-down menu, when the import is complete.
- You can undo a recent list import for any reason.
Problems with File
If MailChimp won't accept your file for upload at all, there are a few possible causes.
Unsupported File Type
If you chose the Import from a CSV or TXT File option, make sure the file you upload is a CSV file or tab-delimited text file. The system does not support of Excel (.xls), ACT!, .vcf (vCard), or other file types.
- Exported files from other ESPs may not be formatted in a way that our import tool can manage, so take some time to review our formatting guidelines.
- Our groups feature only supports 60 groups. If you switch from Constant Contact with 60 groups or more, you may see an error on your import.
Check the OPTIN_TIME or CONFIRM_TIME
You can import OPTIN_TIME and CONFIRM_TIME fields, but they are only checked the first time you import a subscriber and can't be overwritten later. Also, future dates in these fields will cause an error, so double check that this field data is correct.
Malformed or incomplete email addresses are treated as syntax errors, and won't be added to your list. Other syntax errors we remove from your import include unsubscribed and duplicate email addresses. We'll display the number of errors found on the Import History page when the upload is complete.
To fix these addresses, you can view which addresses were removed and add them back individually or as a new import. Click the X emails had syntax errors link on the confirmation screen, or visit the Import History page to view the import history. Upload details are viewable in the account for about 24 hours.
Here are some common causes of syntax errors.
An address could be missing something. For example, john@aol is missing ".com," and john@aolcom is missing the dot. After the address has been corrected to firstname.lastname@example.org, it can be uploaded to the system.
Spaces in the File
An address may include unnecessary spaces, before, after, or even in the middle of the address because of how some export utilities work. These extra spaces can cause an otherwise valid address to be reported as a syntax error. Try the TRIM function in Excel to remove spaces from text, or search your help documentation for a similar feature in your preferred spreadsheet application.
Typos in the Address
Look for typos. MailChimp scans for misspellings of common domains and removes them from your import to prevent bounces. For example, we'll block "email@example.com" or "firstname.lastname@example.org" because Gmail and Yahoo were misspelled. Once you fix the spelling, you'll be able to import the addresses.
MailChimp supports Unicode (UTF-8), ASCII, and extended ASCII characters. You can prevent syntax errors if you import files where the character encoding is UTF-8.
Subscriber Count Doesn't Match
If the numbers on your Import History page don't match what you expected to see, based on your subscriber account, here are two things to look for.
When Auto-Update is turned on, we add new addresses as new subscribers and update existing subscribers' profiles with the new information you import. If an email address appears multiple times in your list import file, we'll import it once as a new subscriber and update that profile with the information in the subsequent rows. For example, if you upload 10 addresses, where a single subscriber's information is included on three rows, your total subscriber count would only be seven.
If Auto-Update was turned on, your list import results will read that "X email addresses were added or updated," instead of just "added."
If you reach the subscriber limit of your current monthly plan while a list is importing, the import process will stop temporarily and send an account upgrade confirmation email to the Primary Account Contact. After an upgrade is confirmed, the import should restart.