Always make a backup of your original CSV file before you make changes. Then continue working in a copy of the file.
How can I make my CSV file as small as possible?
To make sure your file is imported properly, it is best to keep your CSV file as small as possible. This helps prevent errors and can speed up the import.
MailBlue goes through every column and every row in your file during the import, even if you do not plan to map all of the data. The more unnecessary data you leave in the file, the slower your import can become.
Columns: remove all irrelevant columns and only keep columns with information you need in MailBlue.
Rows: remove all empty rows from your file. You can also remove rows without an email address, because contacts are imported based on email address.
How do I format my file correctly?
When formatting your data, there are a few important points to keep in mind. This reduces the chance of import errors and unexpected results.
Date formatting: only use a format with dashes. Do not use spaces or slashes. If the formatting is incorrect, the date can automatically be set to 1899.
Multiple tags for one contact: separate tags with commas, for example Tag1,Tag2,Tag3. Do not use spaces.
Multiple values for one field: for fields such as a checkbox or list box, use a double pipe between values, for example, Value 1||Value 2||Value 3.
Check your email addresses: make sure email addresses are spelled correctly and are properly formatted.
Text formatting: save your CSV file using UTF-8 encoding and avoid special characters that may cause problems during import.
Remove line breaks: make sure there are no line breaks in field values, because they are not supported during import.
No emojis: do not use emojis in cells in your CSV file, because the import may get stuck.
Below is an example of a properly formatted file:
How do I split large contact files into smaller files?
Depending on the number of contacts you import and the number of columns you include in your import, it is best to split large contact files according to the guideline below:
Maximum number of columns | Maximum number of contacts |
1-5 | 250,000 |
6-10 | 150,000 |
11-16 | 125,000 |
17-25 | 80,000 |
26-29 | 65,000 |
30-39 | 50,000 |
40+ | 35,000 |
Import split files one at a time and wait about an hour between larger imports. This makes it easier to spot and solve errors.
Are you moving over from another email provider? You can use MailBlue's free migration service.
Frequently asked questions
Why should I remove empty columns and rows?
Why should I remove empty columns and rows?
A smaller file is processed faster and reduces the chance of errors. MailBlue goes through every column and every row in your file during the import.
How do I add multiple tags or multiple values in one field?
How do I add multiple tags or multiple values in one field?
Separate tags with commas, for example Tag1,Tag2,Tag3. If you use a field such as a checkbox or list box, separate the values with a double pipe, for example Value 1||Value 2||Value 3.
Why do I need to remove line breaks and emojis?
Why do I need to remove line breaks and emojis?
Line breaks are not supported during import, and emojis can cause your import to get stuck. Remove both from your CSV file before you import it.
How long should I wait between large imports?
How long should I wait between large imports?
For larger imports, it is best to import files one at a time and wait about an hour between each import. This makes it easier to identify any errors.