How to merge multiple lists into one
There are two methods for storing your contacts – using segmentation to divide your list into subgroups or creating multiple separate lists. We explain how both of them work in our article about organising your contacts, but in most cases, we recommend keeping a single list in your EmailOctopus account and using segmentation to divide your contacts into subgroups.
If you'd like to switch to a single list approach but have already created multiple lists, you can merge them by exporting the existing contacts and reimporting them to the main list. In this article, we'll guide you through the process and show you how to keep your subscribers tagged so you always know which list they came from.
Tagging and exporting existing contacts
You can tag your contacts using Actions or directly during the import process. If you'd like to do the latter, scroll down to the Importing contacts to your Main list section.
First, choose the list that will act as the main list, or create a new one for that purpose by going into your Contacts tab, selecting "Manage lists", then clicking on the "Create list" button. We called our list "Main list". This will be the list to which we'll add the contacts from all the other ones.
Open one of the lists you want to merge. Click the drop-down icon next to the email address field and choose the “Select all” option.

Once the contacts are selected, click the “Actions” menu above and choose the “Update tags” option.

Choose an existing tag or create a new one under the "Add tags" tab. We will use this tag to identify these contacts when they are added to the main list, so make sure to choose something associated with the current list, like its name. Click “Update” to tag all the contacts.

Once the contacts are tagged, you can then reopen the “Actions” menu and choose the “Export” option.
In the export pop-up, make sure to open the drop-down menu and select all columns to make sure all the data is exported, then click "Export".

If you need the engagement data for the lists you're going to delete, export your reports before you do that, as you won't be able to see the email addresses of your contacts in them once you delete the lists.
Once the contacts are exported, you can delete their source list. Make sure to do this before importing them to your main list to avoid accidentally upgrading your plan to a higher tier.
Go through the above process for all of the lists you want to merge.
Importing contacts to your Main list
Once all the lists are exported and deleted, you can open your new list and import those contacts using the "Import contacts from a file" option.

During the import process, choose to update your contacts if they're already present in the list so that contacts duplicated on multiple lists will all receive the new tag with each import. At this point, you can also tag your contacts if you didn't do so before using Actions. All imported contacts will be tagged if you choose to do it now, during import.

If you tagged your contacts using Actions before instead, find the column with your tags and select “Import comma-separated tags” from the drop-down. If you'd like to import the fields from previous lists, make sure to map them as well. Continue the import process and repeat it for other exported list files.

Once you've imported all contacts, you can send campaigns to contacts with a selected tag, allowing you to choose a group of recipients identical to your original lists.