The article also warns of not being prepared and not catering for gaps in data to avoid awkward empty spaces and bad grammar, but using NewZapp's sorting tools you can see just how wide spread (gappy) your data is and maybe even fix this by adding missing information.
Here are 10 steps to check how many standard data gaps there are in your data:
Go to the Contacts section of you account
Open the Group of contacts you are planning to send to, or All Contacts if that's your intended audience.
Once open the data will load into a table at the bottom of the screen, in columns.
By default the order of the data on screen will be listed by email address in A-Z order.
The first row of the table is made up of all the column headings, and each heading is clickable.
Click a heading to reorder the table data by that particular column
For example, click the "First Name" heading and the data loads in A-Z by first name.
Immediately you will notice of there are empty cells at the top of the column of data, and this indicates how many contacts do not hve a first name stored.
If any of these are easy to rectify, and you know the contact's first name. click on the row with their details and their Contact Card will open.
Edit the details and close.
It's not unusual to have gaps in data, but this doesn't necessarily mean you can't personalise emails to all you contacts. Consider these 3 options:
Use phrases that work regardless of whether the personalisation tag(s) in your email can find data to insert.
Set a default backup for gaps, in Settings / Personalisaiton.
Split your audience into two and create two different emails. Use content without any personalisation tag(s) in one copy of the email. Send this email to the contacts with missing data,