Summary
Plus-tagged email addresses, also known as sub-addressing or email aliases, involve adding a unique string (often preceded by a "+" sign) to the local part of an email address, such as yourname+tag@example.com. This feature has existed for a long time in services like Gmail and Yahoo (using a hyphen in the past), and is now gaining broader support, including in Microsoft Office 365. For email marketers, the rise in usage of these addresses presents both opportunities and challenges, particularly concerning subscription management, analytics, and unsubscribe processes. Ensuring your email platform and internal systems correctly recognize and handle these variations is crucial for maintaining effective communication and compliance.
Key findings
- Widespread adoption: While not new, major mailbox providers like Microsoft Office 365 are increasingly supporting plus-tagging, driving wider user adoption.
- User control: Plus-tagged addresses empower users to filter incoming mail, track which services are sending them email, and identify sources of unwanted mail.
- System compatibility: Email service providers and internal systems must be able to properly process plus-tagged addresses for subscriptions, sending, analytics, and unsubscribes.
- Unsubscribe clarity: It is good practice to display the subscribed email address in the email body to help users identify which specific address to unsubscribe. This also helps with managing multiple preferences.
Key considerations
- Subscription process: Verify that your sign-up forms and backend systems can accept and store plus-tagged email addresses correctly.
- Data management: Ensure your customer relationship management (CRM) and email platforms can consolidate or link multiple plus-tagged addresses to a single user account for unified communication.
- Unsubscribe handling: Confirm that unsubscribe requests initiated from a plus-tagged address correctly remove the user from the appropriate mailing list without impacting other subscriptions tied to the base address. This includes ensuring your one-click unsubscribe functionality is robust.
- Analytics accuracy: Monitor your email analytics to ensure that plus-tagged addresses are not skewing your metrics, especially if unique opens or clicks are tied to the exact email address rather than the core user.
- Deliverability impact: Be aware that some legacy systems or less sophisticated email filters might treat plus-tagged addresses differently, potentially affecting deliverability or increasing the likelihood of being flagged as spam. Microsoft's support helps mitigate this.
What email marketers say
Email marketers often encounter plus-tagged email addresses as users seek more granular control over their inboxes. The general sentiment is that while these addresses offer benefits to subscribers for organization and spam identification, they can introduce complexities for marketers if not properly managed. It is important for marketing platforms to correctly process these addresses to avoid alienating subscribers or missing crucial data points related to engagement and unsubscription behavior.
Key opinions
- Enhanced filtering: Marketers recognize that plus-tagging helps subscribers manage and filter their emails, making their inboxes less cluttered.
- Unsubscribe challenges: The primary concern is ensuring that an unsubscribe request from a plus-tagged address correctly translates to the primary account, preventing unnecessary sends and potential spam complaints.
- Data hygiene: If not handled correctly, plus-tagged addresses can lead to duplicate entries in subscriber lists or inaccurate engagement metrics.
- Subscriber experience: Providing clear unsubscribe options and acknowledging plus-tags contributes to a positive user experience, which is vital for long-term engagement.
Key considerations
- CRM integration: Integrate your email platform with your CRM to ensure all variations of a user's email address are recognized as a single contact.
- Preference centers: Utilize robust preference centers that allow users to manage subscriptions for their primary email, regardless of the plus-tag used for initial sign-up.
- Unsubscribe links: Implement clear and functional unsubscribe links that simplify the process for users, as highlighted by Superhuman's guide on managing subscriptions.
- A/B testing: Test how your email system handles plus-tagged addresses in various scenarios, from subscription to unsubscribe flows.
- Compliance awareness: Stay informed about best practices for managing unsubscriptions, especially concerning mailbox providers that may have specific requirements for handling these addresses, as discussed in our article on how mailbox providers handle unsubscriptions.
Marketer view
Marketer from Email Geeks states that it's crucial to check that current systems can subscribe, send mail to, see analytics from, and allow unsubscribes from plus-tagged email addresses. This is because users are increasingly adopting these addresses for personal email management, making compatibility essential.
Marketer view
Marketer from Medium advises using address tags for better email subscription tracking. By creating a new tag for each service, users can effectively filter emails and identify where their address may have been shared, allowing for better inbox management.
What the experts say
Experts in email deliverability and anti-abuse generally view plus-tagged email addresses as a long-standing, beneficial feature for users. Their primary concern for senders revolves around the backend system's capability to correctly interpret and act upon these addresses, especially for unsubscribe requests. Mismanagement of plus-tags can lead to frustrated users, increased spam complaints, and ultimately, damage to sender reputation or a blocklist listing.
Key opinions
- Standard feature: Experts confirm that plus-addressing (sub-addressing) is a well-established and widely supported feature across major email providers.
- Critical for compliance: Proper handling of unsubscribes from plus-tagged addresses is essential for adhering to regulations like CAN-SPAM and maintaining good sender practices.
- Reputation impact: Failure to process these addresses correctly for opt-out requests can lead to increased spam complaints and negatively impact sender reputation, potentially leading to a blocklist placement.
- Preventing abuse: Users leveraging plus-tags can identify compromised services or those selling their data, making it imperative for legitimate senders to respect their preferences.
Key considerations
- Holistic unsubscribe: Ensure that unsubscribing from a plus-tagged address also unsubscribes the root address from the specific list, as described in managing email spam complaints.
- System testing: Regularly test your subscription and unsubscription processes using plus-tagged addresses to confirm they function as expected across different email clients.
- Address normalization: Consider if your systems should normalize plus-tagged addresses to their root form for identification, while still respecting the full address for specific campaign targeting, or if your system needs to distinguish them.
- User experience focus: Prioritize a seamless unsubscribe experience. This includes clear instructions and immediate processing of requests, which is a core tenet of good email deliverability.
- Understanding RFCs: While RFCs outline email addressing, practical implementation by mailbox providers varies. It's important to understand what RFC 5322 says versus what actually works in practice.
Expert view
Expert from Email Geeks notes that it is already too late for some providers to implement plus-addressing, as Gmail has supported it for a while. They also mention that Yahoo used a hyphen feature (e.g., user-tag@yahoo) in the past, showing these concepts are not new.
Expert view
Expert from SpamResource.com indicates that while plus addressing is a convenient user feature for filtering, it can be a double-edged sword for marketers. Systems need to be intelligent enough to recognize the base email address for comprehensive subscription management, even when a plus tag is used.
What the documentation says
Technical documentation and official guidelines highlight that plus-tagged email addresses are a legitimate and supported feature across various email systems. The emphasis is on the sender's responsibility to correctly interpret and act upon these addresses for deliverability and compliance purposes. This includes ensuring proper handling of subscription, sending, and particularly, unsubscribe requests to maintain a positive relationship with recipients and adhere to anti-spam laws.
Key findings
- Official support: Microsoft, among other major providers, officially supports custom plus-tagged email addresses, reinforcing their validity in the email ecosystem.
- Compliance necessity: The CAN-SPAM Act requires clear and easy unsubscribe mechanisms, which extends to how senders manage requests from plus-tagged addresses.
- User empowerment: Plus-addressing provides a simple method for users to manage their inbox clutter and identify the sources of their emails, thus improving their overall control.
- Unsubscribe mechanism: Effective unsubscribe mechanisms, often including a link in the email body, are critical for users to opt-out, regardless of whether a plus-tag was used.
Key considerations
- System capability: Email platforms should be designed to recognize the base email address when a plus-tag is used for subscription or unsubscription requests.
- Data accuracy: Accurate tracking of unique subscribers, even with variations like plus-tags, is essential for reliable analytics and preventing duplicate communications.
- Preference management: Provide options for users to unsubscribe from specific categories or all communications from a single page, accommodating different email addresses used.
- Legal requirements: Familiarize yourself with and adhere to legal requirements like the CAN-SPAM Act, which mandates clear unsubscribe options for all recipients.
Technical article
Documentation from ZDNet confirms that Microsoft is adding support for custom plus-tagged email addresses in Office 365, noting that this feature was already present in Hotmail. This move signifies broader industry adoption and validation of sub-addressing.
Technical article
Documentation from the FTC's CAN-SPAM Act guide reminds businesses that subscribers have the right to opt out of marketing emails. This applies regardless of whether they used a standard or plus-tagged address for subscription, emphasizing the need for robust unsubscribe processes.
Related resources
11 resources
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