Hello @RobertS82798 ,
You don't need to see all the compressed info in a CSV in order to import it into the system. Having a bunch of extraneous information, including unnecessary formatting of cells, can result in extreme slowness and errors when trying to import that much contact data.
Generally speaking, if you're still struggling to import your file, consider removing columns of info that you don't actually need for your Constant Contact accounts. Or consider splitting the list up into separate files so their sizes reduce.
For more info and advice on properly formatting contact files prior to upload, I'd recommend checking out this article.
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