tl;dr: One works, the other doesn’t. Spam cut from 300/day to nearly zero.
One of my email addresses got in the spammers’ sights sometime last year. The spam volume kept building and building until by the fall it was over 300 per day to this one address, which got only a handful of good emails per day. Time to do something serious about it.
I began saving up the spams day by day and recording the daily counts (see figure; click for a larger version). Then I turned on the free version of Heluna, which is accomplished by setting the domain’s first and last (4th) MX records to point to a Heluna server that simply refuses every connection. Real mail will try others of the MX records but spammers mostly won’t, the theory goes.
This made a dent in the spam volume, cutting it not quite in half. (Heluna claims on their site that you might see up to 90% reduction. Nowhere close to that.) The results looked encouraging enough that I was willing to spring for the pay version at $49 per year. Another change in MX records and Heluna began filtering all messages to the subscribed address. The promised spam reduction here was in the high 90s; what I saw over a couple of months was more like a 66% reduction.
With Heluna there is no training and no UI to look through lists of false positives or missed spam. All the effort at distinguishing spam happens in their cloud (or black box perhaps). This is nice in terms of reduced effort on the customer’s part, but it doesn’t provide the advantage of learning patterns in that one particular spam stream.
I was ready for stronger medicine.
I had activated the Spamhero service for one client but hadn’t investigated how well it worked in any detail. So I signed up for a trial, resetting my MX records to go through Spamhero’s servers.
The spam level more or less immediately fell by half, to 25% of where it had started. Promising. I subscribed to Spamhero and secured a refund from Heluna.
It turned out that I had a misconfiguration in Spamhero’s simple setup, and when I fixed that a few days later, spam levels immediately dropped by half again.
Things went on at this level for another 10 days while I trained the service. This is accomplished simply by forwarding each spam that slips through to an address unique to the account. Within a couple of weeks the spam level had fallen to the single digits per day, and a week ago I had my first day of zero spams. It has been in the low single digits since.
I have never seen a false positive — good email mistakenly marked as spam. The algorithms are biased in favor of safety, and I appreciate that very much.
The Spamhero UI is quite accomplished. You can review mail that was classified as good and mark any spams that got through. (This is an alternative to forwarding the bad emails to the missed-spam address.) A dashboard gives you a quick view of the last 90 days’ worth of statistics: numbers of spam and ham and the quality of the service’s filtering. You can manage multiple accounts from the same UI.
Spamhero costs $4.95 per month if paid annually, and $6.95 if monthly.
Disclaimer: I have no affiliation with either of the services reviewed here. I'm just an enthusiastic customer of Spamhero.