The easiest and full-proof approach to avoiding SPAM traps of any type is to run a double opt-in program, but they come with significant value costs. Other ways to to manage SPAM traps:
Remove unengaged email addresses periodically
Don't scrap email addresses
Don't buy email addresses from unreputable sources.
Use caution when buying from reputable sources and then clean your list
Monitor spam trap hits and try to identify SPAM trap recipient, with a focus on phishing and pristine traps.
Because of private ESP spam traps, it's impossible to identify and remove all spam addresses. Double opt-in and removing unengaged email addresses are the most effective ways to manage SPAM traps.
There are a few general accept types of SPAM traps
Phishing
Pristine (or pure): Email addresses that have never been used by anyone and are typically only picked up by website scrapping. These are the most damaging. If you generally follow best practices, you probably picked it up as a typo or as a fake address.
Recycled: These are previous valid email address that have gone into disuse. On average, a mailbox provider creates recycled spam traps after 3-9 months of inactivity.
Typos:
Invalid (or fake): These are wild cards. A recipient provided a fake address and hopefully its a non-existent domain. Otherwise it could be a SPAM trap of a type of any of the above.
Spam trap hits lower your spending reputation and can land you in the spam folder.
Being proactive in not adding SPAM trap address is ideal:
Weight the cost/benefits of running a double opt-in program
Don't scrap email addresses
Don't buy email addresses from unreputable sources.
Caution when buying from reputable sources and then clean your list
Run all email addresses through an email list validation service to identify malformed and misspelled domains, unknown users and temporary email addresses.
These are all potential sources of spam traps.
It's not always possible to avoid acquiring a SPAM trap email addresses. In those cases:
Remove unengaged email addresses periodically
Have a plan to identify unengaged subscribers from the moment they sign up. Send win-back campaigns with special offers to these subscribers and suppress any that don’t engage with the email by opening it or clicking through to your website.
Send re-permission campaigns. Send your unengaged subscribers a campaign asking them to re-confirm their commitment to receiving your email by clicking a link within the email. Send them to your preference center and ask them to confirm their choices on your website. Spam traps will not complete these actions. Suppress any email address that does not re-confirm.
Monitor spam trap hits and try to identify SPAM trap recipient, with a focus on pristine traps.
Remove all unknown users after one bounce. Most mailbox providers bounce back an inactive email address as an unknown user for 3-9 months prior to creating it into a recycled spam trap.
Sign up for Microsoft’s Smart Network Data Services (SNDS). SNDS provides detailed times for sending email to Microsoft spam traps. You can use this information to identify potential sources of the spam trap by comparing the time the spam trap was hit to the times your email was sent. Suppress unengaged email addresses sent at the same time the spam trap hit was recorded.
Use Return Path’s Certification Whitelist and Return Path Platform Sender Score data to identify specific IP addresses that may be a source of the spam traps. This is especially effective when you segment your IP addresses for different email streams.
Segment your email list and send to different segments on different days and at different times. Use Return Path’s Certification Whitelist, Return Path Platform Sender Score and Microsoft’s SNDS data to identify email segments suspected of containing a spam trap. Continue segmenting and sending to different segments on different days or times. At some point, the segments will be small enough where you can suppress the entire segment that has the spam trap.
Check your triggered message program. Sending annual emails for birthdays, anniversaries and product renewal reminders can be a source of hitting spam traps. Look for signs of engagement for all subscribers receiving these emails and suppress any email address that has not engaged within the last 6 months (you may have to be more aggressive and go to 3 months or less depending on the severity of the problem). With an effective win-back and re-permission program, only your engaged subscribers should be receiving these triggered emails.
Subscribe to a reputation service
Monitor SPAM hits
Depending on your ESP, you might be able to trace back to the email address by:
the from or return address
a personalized subject line
SPAM reporting data (Google FBL and Microsoft SNDS)
Data and time of the send
Segmentation. Delivery and engagement indicators
IP address
sender info
Past bounces
Opens and clicks
Follow-ups:
Micro personalizing the subject or from addresses
Without any other indicators, aging out unengaged email addresses is the only way to remove spam traps from your list. Removing unengaged audiences from your general distributions will help keep your messages from going to the spam folder. If you are worried about potentially leaving money on the table, it's okay to try to re-engage cold lists, but it's probably a good idea for these messages to be targeted and occasional.
Are you able to offer any insight in regards to this diagnosis/strategy? If your ESP supports it, use Variable Envelope Return Path (VERP). Otherwise, try personalizing the messages directly or indirectly to identify the trap. Add a name to the subject. If you your email system can handle it, add a unique ID into the from address (e.g. alumniengagement@albion.edu becomes alumniengagement+123456@albion.edu). Realize though that spam trap monitoring only catches part of the problem. Mailbox providers have private spam trap networks not exposed to the public.
Are there any tools you recommend we use to maintain healthy lists?
We use 250ok to monitor and for other deliverability services. Mxtoolbox is great specifically for this kind of monitoring. Here is link to some 250ok competitors: https://www.spamresource.com/2020/03/other-deliverability-monitoring-vendors.html
Segmenting your lists by last engagement
Reputation monitoring through Google Postmaster, but requires aligning SPF and DKIM authentication for all your sending services
Setting up complaint feedback loops
I'm aware of, but not familiar with, Microsoft's Smart Network Data Services. I need to do some work here to learn and configure it. SNDS is great if you own the IP addresses, but with imodules you probably are on a shared range and will not be able to configure it.
Sources