What is a subscriber key in Salesforce Marketing Cloud?

A subscriber key in Salesforce Marketing Cloud is a unique, alphanumeric identifier that distinguishes each subscriber. Unlike an email address, which can change, the subscriber key remains constant and is used to associate all data and interactions with a specific individual across the SFMC platform.

Can I use existing subscriber keys for eData Source seed list entries?

You can use existing subscriber keys if your eData Source seed addresses correspond to known contacts with established subscriber keys in SFMC. However, if your seed list contains addresses that don't have existing SFMC records or unique IDs, you'll need to generate a new unique identifier for each. Often, using the seed email address itself as the subscriber key is a practical solution for testing purposes.

How often should I update my eData Source seed list in SFMC?

The frequency depends on how often your seed list is updated by eData Source and your testing needs. It is a good practice to update your seed list in SFMC whenever there are significant changes to the eData Source list or at least on a regular schedule, such as weekly or bi-weekly, to ensure your monitoring is always accurate.

What happens if I don't use unique subscriber keys for seed addresses?

If you do not use unique subscriber keys for your seed addresses, SFMC may default to using the email address. This can lead to issues if the same email address appears in multiple lists with different data, or if you later change an email address. It can result in duplicate contact records or incorrect data being associated with the seed address, making accurate deliverability tracking difficult.

How to upload eData Source seed lists to Salesforce Marketing Cloud and manage subscriber keys? - Technical - Email deliverability - Knowledge base

Email deliverability relies heavily on knowing where your emails land. This is precisely why seed lists are so critical to an email program, providing insight into inbox placement rates. When working with eData Source and Salesforce Marketing Cloud (SFMC), one of the initial hurdles is effectively uploading your seed list while correctly managing subscriber keys. SFMC’s unique approach to identifying subscribers requires careful consideration to ensure your seed emails are properly integrated and trackable.

The main challenge often stems from how SFMC handles subscriber identification. Unlike some platforms that simply use an email address as the primary identifier, SFMC uses a concept called the subscriber key. This key is a unique, persistent identifier for each subscriber across the entire Marketing Cloud platform, and it dictates how all interactions and data points are associated with that individual. Ignoring this can lead to fragmented data and inaccurate testing results.

In this guide, I will walk through the process of taking your eData Source seed list, preparing it for Salesforce Marketing Cloud, and ensuring that your subscriber keys are set up correctly. This will help you leverage your seed list for accurate inbox placement monitoring and overall email deliverability improvements.

The importance of subscriber keys in Salesforce Marketing Cloud

In Salesforce Marketing Cloud, the subscriber key is the foundational identifier for every contact. It is a unique text value, often an email address, but it can also be a customer ID, loyalty number, or any other unique string. This key is crucial because it ensures that all subscriber data, including preferences, send history, and engagement metrics, are consistently tied to the correct individual, even if their email address changes over time. Understanding this concept is fundamental for effective data management in SFMC.

The distinction between an email address and a subscriber key is important for deliverability testing with seed lists. While your seed list will contain email addresses, SFMC needs a corresponding subscriber key to properly associate those addresses with a subscriber record. If you don't define a subscriber key, SFMC typically uses the email address as the default, but this can cause issues if you later need to change an email address or track a subscriber across multiple email addresses.

Properly managed subscriber keys are key to maintaining data integrity. If your subscriber key strategy is inconsistent, SFMC may create duplicate records or fail to update existing ones, leading to inaccurate reporting and potentially impacting your ability to track email engagement for your seed addresses accurately. This can obscure deliverability issues and make it harder to troubleshoot problems like emails going to spam or blocklists (or blacklists).

Best practice: Subscriber key setup

Always define a clear, consistent subscriber key. For many marketers, an external ID or a unique customer ID is more robust than relying solely on the email address. This provides flexibility and better data management over time.

When importing a new list, verify that your import file contains both the email address and your chosen subscriber key to avoid default behaviors that might create unintended duplicates.

Structuring your eData Source seed list for SFMC

When you receive a seed list from eData Source, it will primarily consist of email addresses. However, for seamless integration into Salesforce Marketing Cloud, you will need to ensure each seed email has a corresponding subscriber key. If your system already uses unique customer IDs or member IDs, you can simply assign one of those to each seed address. If not, you may need to generate unique identifiers specifically for your seed list entries.

One common approach, especially when you don't have existing IDs, is to use the seed email address itself as the faux subscriber key (or member ID), as discussed by users in the Email Geeks community. While this might seem counterintuitive if your standard subscriber key is not an email, it works for seed lists because these addresses typically do not represent actual customer records that need complex, long-term tracking. The goal is simply to get them into SFMC in a trackable way.

Once you have decided on your subscriber key strategy, you need to prepare your seed list file. The simplest way is to create a CSV file with at least two columns: one for the email address and another for the subscriber key. Additional columns for other attributes like 'seed type' or 'source' can also be beneficial for segmenting your seed list in SFMC and for managing multiple content versions.

Column name	Example value	Description
EmailAddress	seed1@example.com	The email address of the seed.
SubscriberKey	seed1@example.com	The unique identifier for the subscriber.
SeedSource	eData Source	Optional: Source of the seed address.

Uploading your seed list to Salesforce Marketing Cloud

Salesforce Marketing Cloud offers several ways to import data, but for seed lists, using a data extension is generally preferred over a simple list. Data extensions provide more flexibility for storing additional attributes and are essential for advanced segmentation and automation. You can create an import activity to automate this process.

To upload your prepared CSV, navigate to Email Studio, then Subscribers, and select Data Extensions. Create a new standard data extension, ensuring you define fields for EmailAddress and SubscriberKey, and set the SubscriberKey as the primary key. This is a crucial step for accurate tracking and avoiding duplicates. Marketing Cloud also provides enhanced subscriber features if needed.

When configuring the import, map the columns from your CSV to the corresponding fields in your data extension. Ensure the EmailAddress field is set to the EmailAddress data type and SubscriberKey is set as a Text field and the primary key. For efficient data management, you might consider using Marketing Cloud Connect for subscriber key migration.

Sample data extension definition for seed listJSON

Name: SeedList_eDataSource
External Key: SeedList_eDataSource_Key
Fields:
- Name: EmailAddress, Data Type: EmailAddress, Nullable: False
- Name: SubscriberKey, Data Type: Text, Primary Key: True, Nullable: False
- Name: SeedType, Data Type: Text, Nullable: True

Integrating seed lists into your sends and ongoing management

Once your eData Source seed list is successfully uploaded to a data extension, the next step is to integrate it into your email sends. The easiest way to do this is by including the seed list data extension in all your standard sends. In Email Studio, you can add this data extension as an additional recipient list when configuring your email sends. In Journey Builder, you would ensure your Journey's entry source includes contacts from this data extension, or you can add a separate send activity specifically for your seed list if you prefer to send a different version.

Ongoing management of your seed list is just as important as the initial upload. Regularly update your seed list data extension with fresh addresses from eData Source and remove any addresses that are no longer active or necessary. This ensures your monitoring is always based on current, relevant data. Continuous monitoring of your inbox placement and checking for any appearances on a blocklist (or blacklist) will provide valuable insights into your email program's health.

Beyond simply sending, actively use the data you get back. Analyze the deliverability reports for your seed sends and identify patterns. If you see consistent spam folder placements, it is a sign that you might need to diagnose and fix deliverability issues in SFMC. Remember, the goal of using seed lists is not just to see where emails land, but to take action on that information to improve your overall sender reputation.

Good practices

Consistent keys: Use a unique, stable subscriber key for all seed addresses.
Dedicated data extension: Maintain a separate data extension for your eData Source seed list.
Regular updates: Keep your seed list current by adding and removing addresses as needed.
Integration: Include the seed list data extension in all relevant sends.

Common pitfalls

Defaulting to email: Letting SFMC use email as subscriber key if your system has other IDs.
Mixing data: Importing seed addresses directly into active subscriber lists or data extensions.
Infrequent updates: Using outdated seed lists that don't reflect current deliverability trends.
Ignoring results: Not analyzing inbox placement data to inform deliverability strategy.

Views from the trenches

Best practices

Always use a dedicated data extension for seed lists in SFMC, separate from your main subscriber data.

Map subscriber keys consistently, even if you generate faux IDs for your seed addresses.

Schedule regular imports to keep your eData Source seed list updated within Marketing Cloud.

Monitor your seed list results proactively to identify and address deliverability issues quickly.

Common pitfalls

Allowing SFMC to auto-assign subscriber keys, which can lead to inconsistencies.

Not clearly defining subscriber key during initial data extension setup.

Failing to include the seed list in all relevant email sends for comprehensive testing.

Neglecting to remove old or inactive seed addresses from your testing pool.

Expert tips

Consider using a consistent naming convention for your seed list data extensions to easily identify them.

Automate the seed list import process using SFMC's Automation Studio for efficiency.

Use segmentation within your seed list data extension to test different email content variations.

Cross-reference seed list results with other deliverability metrics like bounce rates and spam complaints.

Marketer view

Marketer from Email Geeks says they uploaded their eData Source seed list to SFMC and used the seed email addresses as faux member IDs for the subscriber key. This approach proved effective for their needs.

2019-10-25 - Email Geeks

Marketer view

Marketer from Email Geeks says their setup is similar, with separate MBR_ID and EMAIL fields for the seed list, which they then add to all sends. This method works well for monitoring.

2019-10-26 - Email Geeks

Final thoughts on managing your seed lists

Successfully uploading eData Source seed lists to Salesforce Marketing Cloud and managing subscriber keys is an essential part of any robust email deliverability strategy. By understanding the critical role of subscriber keys in SFMC and diligently preparing your seed list data, you can ensure accurate and consistent deliverability insights.

Whether you choose to use pseudo-IDs derived from email addresses or leverage existing unique identifiers, the key is consistency. A well-structured seed list, properly imported into a dedicated data extension, provides the foundation for reliable inbox placement testing and helps you stay on top of potential issues like being added to a blocklist (or blacklist).

Remember, email deliverability is an ongoing process. Consistent seed list management and proactive monitoring are crucial for ensuring your messages reach the inbox effectively and maintain a strong sender reputation.