What should I do with trade show contacts in Mailchimp without explicit opt-in?
Matthew Whittaker
Co-founder & CTO, Suped
Published 26 Apr 2025
Updated 17 Aug 2025
7 min read
Collecting contacts at trade shows and networking events is a powerful way to grow your business network. It's exciting to meet potential clients and gather their information, with the intention of nurturing those relationships through email.
However, a common challenge arises when these contacts are added to email marketing platforms like Mailchimp without a clear, explicit opt-in. While they might have provided their business card or verbally expressed interest, this often doesn't meet the strict consent requirements of many Email Service Providers (ESPs) or global data protection regulations.
This situation can put your email deliverability and even your account at risk. It's crucial to understand why explicit consent matters and how to handle existing contacts while implementing compliant strategies for future growth.
The imperative of explicit consent
Explicit consent means that an individual has clearly and affirmatively agreed to receive specific types of communications from you. This is distinct from implied consent, which might be assumed through a business interaction but doesn't explicitly grant permission for marketing emails. For example, simply receiving a business card at a trade show is typically considered implied consent for direct business communication, but not necessarily for ongoing newsletters or promotional content.
Platforms like Mailchimp maintain a very strict explicit consent policy. Their terms of service require verifiable proof of consent for any commercial or marketing emails you send. Without this, you risk account suspension and significant deliverability issues.
Beyond platform rules, complying with regulations such as GDPR, CAN-SPAM, and CASL is vital. These laws govern how you can collect and use personal data for marketing purposes. Ignoring these can lead to heavy fines and legal repercussions, not just deliverability problems.
Mailchimp's strict policy
Mailchimp requires verifiable consent. Adding contacts without it can lead to account suspension and deliverability problems. Trade show badge scans or business cards alone are generally not considered explicit consent.
Evaluating your existing trade show list
For existing contacts, especially a smaller list of around 400, Mailchimp might not flag your account if you have good engagement rates and very few complaints. It's often the volume of unengaged sends or high complaint rates that trigger their automated systems for review.
However, operating in this grey area (or perhaps black area) is still a risk. Even with a low volume, you're essentially relying on the ESP not noticing a deviation from their terms of service. This carries potential hidden costs, such as hitting spam traps or being reported by recipients who don't recall opting in, even if they initially seemed interested.
The best approach is to assess the health of this existing list. Monitor your open rates, click-through rates, and crucially, your complaint rates. Low complaints are a good sign, but it doesn't absolve the need for proper consent. If you're concerned about users who may have been opted-in without consent, it's essential to understand the diagnosis and solutions for low open rates and other issues.
Risks of non-compliant lists
Account suspension: Platforms like Mailchimp can suspend accounts for non-compliance.
Poor deliverability: Increased bounce rates and spam complaints can lead to messages landing in the junk folder.
Legal penalties: Fines under regulations like GDPR, CASL, or CAN-SPAM.
Damaged sender reputation: This can affect all your email sending, not just marketing.
Benefits of compliant lists
Higher engagement: Emails reach recipients who truly want to hear from you.
Improved sender reputation: Better inbox placement rates and fewer blocklistings.
Legal safety: Compliance with global email marketing laws reduces legal risk.
Sustainable growth: Builds a loyal and responsive audience over time.
Implementing compliant opt-in strategies
Moving forward, it's essential to implement robust and compliant opt-in strategies for all new contacts. This ensures you build a healthy, engaged list from the start, mitigating future risks. Setting up a dedicated kiosk or iPad at events with a clear sign-up form is a great first step. Ensure the form clearly states what subscribers will receive, aligning with best practices for email marketing opt-in buttons.
Modern solutions like QR codes or Near Field Communication (NFC) 'tap-to-sign-up' can streamline the process, making it easy for attendees to opt-in directly from their smartphones. Display these prominently on your booth, banners, or even business cards. This provides a verifiable record of consent.
Additionally, consider implementing double opt-in (DOI) for new sign-ups. While not legally required by all regulations (like CAN-SPAM), it's a gold standard for confirming genuine interest and preventing accidental or malicious sign-ups. Mailchimp provides tools to help collect consent with GDPR forms. If you're looking into disabling double opt-in, be aware of the associated risks and mitigation strategies.
Future-proofing your list
Clear signage: Explicitly state what recipients will receive upon signing up.
Digital signup forms: Use tablets, QR codes, or NFC for easy, documented opt-in.
Double opt-in: Recommended for stronger consent verification and cleaner lists.
Privacy policy link: Make your privacy policy accessible at the point of sign-up.
Managing existing non-opt-in contacts
Deciding what to do with the existing non-opt-in contacts, especially a small list like 400, can be tricky. The safest and most compliant route is to send a re-permission campaign. This involves sending an email asking contacts to explicitly confirm their desire to receive emails from you. While this might lead to a smaller list, it ensures everyone on it is genuinely interested and compliant.
However, if your current engagement rates are very good and you're receiving minimal spam complaints, some might argue against poking the sleeping bear. This approach relies on the idea that if there are no red flags, Mailchimp may not actively scrutinize a small, well-performing list. This doesn't eliminate the risk, but it acknowledges the practical realities of managing email lists.
Regardless of your approach for the existing list, it's a good idea to segment these contacts to differentiate them from new, explicitly opted-in subscribers. For any unengaged contacts, consider implementing email marketing best practices for unengaged subscribers, which might include re-engagement campaigns, suppression, or opt-out options.
Approach
Pros
Cons
Recommendation
Send Re-permission Campaign
Full compliance, reduces risk of penalties, builds a highly engaged list.
Significant list shrinkage, potential for low response rates.
Ideal for stricter compliance. Proceed with a targeted, value-driven message.
Continue Mailing (with care)
Maintains current list size and engagement if complaints are low.
Ongoing compliance risk, potential for future account issues and blocklistings.
Only if current engagement is exceptionally high and complaints are negligible. Immediately adopt new opt-in practices for future contacts.
Segment and Re-engage
Isolates active users, allows targeted re-engagement for other segments.
Requires careful segmentation and ongoing monitoring.
Good for larger lists, but still a valid strategy for smaller ones to improve overall health and engagement.
Beyond Mailchimp: overall deliverability and blocklists
While Mailchimp's policies are a key consideration, the underlying principles of good email deliverability apply universally, regardless of your ESP. Maintaining a clean, actively opted-in list isn't just about avoiding platform suspensions, it's about ensuring your emails actually reach the inbox.
Sending to contacts without proper consent can lead to increased spam complaints, high bounce rates, and low engagement. These are significant negative signals to Internet Service Providers (ISPs), which can damage your sender reputation. A poor sender reputation can result in your IP address or domain being placed on an email blocklist (or blacklist). When your domain is on an email blacklist, your emails may be blocked or sent to spam folders, severely impacting your outreach efforts across all campaigns.
Proactive monitoring of your email deliverability is key. Regularly check your sender reputation and analyze DMARC reports. These tools provide valuable insights into how your emails are performing and can help you identify and address potential issues before they escalate into major deliverability problems. Understanding why your emails might be going to spam is crucial for maintaining a healthy email program.
Views from the trenches
Best practices
Always prioritize getting explicit consent for new contacts going forward, ensuring clear communication.
Monitor engagement and complaint rates very closely for any list you email to identify potential issues early.
Use digital sign-up methods like kiosks, QR codes, or NFC at events for verifiable consent.
Segment your audience to identify and manage different levels of consent, particularly for older lists.
Common pitfalls
Proactively contacting ESP support to admit terms of service violations for a small, unproblematic list.
Assuming verbal consent or business card exchange equals explicit opt-in for marketing emails.
Ignoring low-volume, high-engagement non-compliant lists, as this can still lead to future issues.
Adding contacts from purchased lists or trade show CSV files without confirmed, explicit consent.
Expert tips
For low-volume, high-engagement lists, ESPs often don't flag non-compliance if there are no red flags.
Consider if Mailchimp is the best long-term fit if your business frequently acquires contacts without explicit opt-ins.
Mailchimp's mobile app and QR code generator are great tools for collecting consent at events.
Even if double opt-in isn't legally required, it's a strong best practice for consent verification.
Expert view
Expert from Email Geeks says that if the contacts provided their email addresses at events, it's generally considered a form of opt-in by some platforms like Mailchimp, especially for a small list of 400 contacts.
August 29, 2024 - Email Geeks
Expert view
Expert from Email Geeks says that for a small list of 400 contacts with low complaints and regular mailings, an immediate opt-in pass may not be necessary. It is crucial to improve practices going forward and tag existing contacts by their permission level.
August 29, 2024 - Email Geeks
Navigating compliance for sustainable email growth
Navigating the complexities of email consent, especially with trade show contacts, is crucial for long-term email marketing success. While the immediate impulse might be to simply add everyone to your list, understanding and adhering to explicit opt-in requirements is essential for maintaining a healthy sender reputation and ensuring your emails reach their intended recipients.
The safest path involves adopting compliant methods for all new contacts and carefully managing existing lists. This dual approach minimizes risks with platforms like Mailchimp and sets a strong foundation for sustainable email growth. Prioritizing consent builds trust with your audience and contributes to overall email deliverability.
Mailchimp without a clear, explicit opt-in. While they might have provided their business card or verbally expressed interest, this often doesn't meet the strict consent requirements of many Email Service Providers (ESPs) or global data protection regulations.
