Official comment
Our postmaster, Brendan Dubbels, provided this answer:
The easy way out here would be to say "Well, that's because everyone knows InfusionSoft's delivery team sucks" and you have nothing to worry about here.
But that's not the truth and it's not that simple.
There are certain things that all ESPs must to do even be considered as a contender for your business when it comes to email. Of course we can all boast about how our company will get you better delivery rates than another but in the end it mostly comes down to the individual mailer. The things that we ESPs can take care of for you are:
- Authentication (SPF, DKIM, and DMARC where necessary)
- Set Low Compliance Rates (ONTRAPORT's are .1% max complaint rate and 7% max bounce rate)
- Removing Problem Clients
- Monitoring Blacklists
- Managing IP Reputation (All IPs should always be in the mid to high 90's at the lowest)
- Feedback Loop Management
Beyond that, it's on the individual mailer to take care of things like list hygiene, domain reputation, email content, and contact engagement. We supply an infrastructure that allows our customers the possibility of 100% inbox ratings if they are following best practices. Unfortunately most marketers are blissfully unaware of their email and list transgressions.
In his case it sounds like he received some lackluster support at IS which is a bummer. Especially when it comes down to Email Deliverability which is generally a frustrating endeavor for anyone not sitting at a workstation with direct SMTP log access. It also sounds like he really dug the interface at ConvertKit as well.
We do see users get deliverability bumps or declines when migrating - but this is generally because anyone who had positive engagement on a separate IP (or had whitelisted the sender) is now moving to a fresh sending environment - which often means a new whitelist needs to be added (depending on provider).
It also sounds like IS may do Spam Filtering a little different than we do. We try to avoid cutting broadcasts short at all costs, as a general rule if a large send gets a few complaints early on it means that there wont be many more to follow. This is especially true for lists that have been mailing consistently with us.
If a user complains, we unsubscribe them. So seeing huge complaint spikes is extremely unlikely unless you start getting bad traffic at your opt in forms or send a completely unrelated pitch to your list.
As far as How you can prevent dips in deliverability in your business just make sure you're up to best practices in you're marketing and you'll be great, consistency is key. To rehash those items from above they are:
- List Hygiene - Is your list segmented so that only the right offers go to the right segment?)
- Domain Reputation - Is anyone else mailing on behalf of your domain - one bad affiliate can cause your mail to go to Spam)
- Email Content - Are you using a spam checking tool on your messages and running a render across multiple platforms to make sure it's readable by all who receive it?
- Contact Engagement - Are you actively removing those that haven't opened, clicked, or purchased in longer than 6 months?
Admittedly I skimmed the article picking up the key portions about delivery - but it seems like there was a lot more to his decision than just email.
He also states that he's no an adviser and uses exclusively affiliate links when linking to ConvertKit so be sure and take this article with a grain of salt.