Every business has lists living outside the system: business cards collected at a fair, the ledger accounting keeps, a customer file from a dealer. They sit in Excel and nobody touches them, because "importing is hard".
Importing is not the hard part; fixing the file beforehand is.
Four checks before importing
Is the number column in one format? Excel reads numbers as numbers and strips leading zeros. "0532..." becomes "532...". Make sure the column is formatted as text before importing.
Are first and last names separate or combined? In one cell, how to split is ambiguous. How do you split "Ahmet Mehmet Yilmaz"? Importing as a single field and correcting later beats splitting wrongly.
Are there duplicates? Rows repeating inside the file become duplicate records after import.
Is there consent? This is the most important check and it is not technical. Calling a purchased list carries legal and reputational risk precisely because consent is absent.
Column mapping
The heart of an import is mapping file columns to system fields. Two mistakes are common:
- Trying to map every column. If the file has forty columns you do not need all forty. Take what is useful and leave the rest.
- Mapping to the wrong field. Mapping a "Company" column to the person's name, for instance. Opening the first ten records after import catches this within minutes.
Try a small slice first
Instead of importing a thousand-row file directly, split off the first twenty rows and import those. Then check: did fields land correctly, are numbers readable, were duplicates created?
A mistake made with twenty records is reversible; one made with a thousand takes days.
Import with a tag
Give every import its own tag: something like "fair-sept-2026". That tag does three jobs: you can build the campaign on that list, you can measure its results, and if something goes wrong you can find every record from that import at once.
An untagged import disappears into the general pool within a week.
Do not call immediately after importing
Calling a trade fair list the next day is right; never calling a purchased list is right. For the in-between cases — an old customer list, a dealer's file — a written contact first is more appropriate.
Also confirm after import that fields like country, source and owner are correctly populated; the campaign will be filtered on them.
The reverse direction: exporting
Getting a list out is a need too — reporting, accounting, backups. One rule applies: an exported file carries customer data and leaves your control the moment it is shared. Who may export should be restricted by permission.
Tomorrow we look at exactly that: who sees which customer.