Andrew, thanks for sharing tips from your search so far. Many ESPs definitely specialize in serving brands of a certain size. Best of luck narrowing down your decision.
Scott, it's a huge decision for sure, so it's no time to skimp on the process. I particularly like how you got the ESPs' developers and product managers into your interview process and didn't rely solely on what the salespeople were telling you. I also like how you used the Nos on your checklist of features to give you leverage on price. That's smart! Thanks for sharing.
Sadie, thanks for sharing your tips! I really like creating a "bad list." Sound like another way to make sure you don't end up with the same problems that drove you to switch in the first place.
Josh, I'd recommend putting a limit on how often an opt-in confirmation request could be sent to a particular email address.
For instance, you might limit it to one every seven days. And, again, I don't recommend sending more than one opt-in confirmation request email for each signup.
Yes, emails get buried quickly, but not that quickly. Plus, it's easy to search for a brand's emails. I'd be wary of an email address that was used to sign up for your emails multiple times but never confirmed any of the signups.
I'd highly recommend looking at any data you have to see just how big of an issue this is for your brand.
The law is hazy on this issue, but I highly recommending only sending one opt-in confirmation request email in response to a single signup form completion or box check. And obviously send that confirmation request immediately.
There are a few reasons to only send one:
(1) People are very familiar with how opt-ins work. As long as you make it clear during the signup process that they should look in their inbox for an email to confirm their subscription, the vast majority of people who do indeed want to subscribe will go and do that.
(2) Sometimes people change their mind about signing up, or got confused about what they were signing up for in the first place. So just because someone doesn't confirm, it doesn't mean that you lost out on a subscriber because of the process. Sending multiple opt-in confirmation requests to these people may cause them to report your emails as spam to make them stop.
(3) As you alluded to, sometimes bots and other forms of malicious signups do take place. Bots are way more common that targeted malicious signups, but you certainly don't want to send multiple opt-in confirmation requests to people who never signed up in the first place. They will totally mark your emails as spam.
Are there people who get distracted and not confirm a signup that they wanted? Yes. But in trying to convert those people with additional opt-in confirmation request emails, you risk spam complaints from the other groups of people discussed above. It's not worth the risk.
If you feel that your opt-in confirmation rate is too low, then review your messaging at signup, on post-signup webpages, and in your opt-in confirmation request email. Don't clutter up that line of messaging with secondary messages or competing CTAs. Focus on getting that confirmation.
Regarding multiple opt-ins without confirmation, consider putting a limit on how often that opt-in confirmation request email can be sent to the same person.
I don't have any stats at my fingertips, but in general the rule has been that you can expect about a third of your email subscribership to turn over every year. Some of that is due to people abandoning their email accounts or leaving them when they change jobs. The latter certainly elevates that factor for B2B companies.
Litmus' 2017 State of Email Deliverability report touches on verification services:
Our research found that BriteVerify and FreshAddress were the most popular providers by far.