I used to work at an email service provider that managed email marketing campaigns for some pretty large companies. It's been quite a number of years now, but I don't imagine things have changed all that much.
Mostly, it's just CYA language because of the way the various old and slow systems work, plus the CAN-SPAM act legally allows up to 10 days to process an unsub.
There are multiple checkpoints that prune lists as they get churned through the machine, so typically you'll be fully unsubbed within 24 hours (often much less), but they don't catch all cases at all times.
The abbreviated process for sending out a marketing campaign at a large ESP typically looks like:
- Marketing manager makes a request for a list of people that match x/y/z analytics criteria (e.g., purchased within last x months, typically opens email, geographic region, etc). Depending on how "sophisticated" the criteria are and how backed up the analyst department is, this may take a couple of days to get turned around.
- The list of addresses is created and then pruned down by known unsubscribes or other do-not-email constraints in the system at the time the query runs.
- The resulting list gets sent out for review and approval by the marketing manager and client (how many people are we going to mail, what is it going to cost, what sort of metrics do we expect, etc). Since this is a human-in-the-loop process, it may again take up to several days to turnaround.
- After approval, the list gets churned through the unsubscribe list again, dropping any new unsubs. This step should catch new unsubs within that "it may take up to few days" window mentioned in the title.
- The final list is then queued up for sending, which depending on the size and meter rate may go out over the course of several hours. If you've already been queued up your unsubscribe request is typically going to get missed for this run.
Now, add on the complexity of syncing up multiple databases between the ESP and the customer, which is typically a nightly batch job at best. So even though your unsubscribe hit some web server instantly, it may take a couple of days for it to fully filter through from the web server to the client's marketing databases into the ESP's database. It's similar to why banking and ACH is so terrible: it's just ancient design patterns and slow process and nobody wants to pay money to modernize it. And if they miss a few unsubs they are still well within the legal bounds so it's whatever.
tl;dr: A lot of email marketing still runs on chains of batch jobs which can introduce windows of unsynchronized lists getting sent out.
It 100 percent is still this way. But generally your queued list can be set up 1-2 days beforehand, so that's why it's often 48-72 hours, because you're already in that list that's been cleaned at the provider for drop.
Mostly, it's just CYA language because of the way the various old and slow systems work, plus the CAN-SPAM act legally allows up to 10 days to process an unsub.
There are multiple checkpoints that prune lists as they get churned through the machine, so typically you'll be fully unsubbed within 24 hours (often much less), but they don't catch all cases at all times.
The abbreviated process for sending out a marketing campaign at a large ESP typically looks like:
- Marketing manager makes a request for a list of people that match x/y/z analytics criteria (e.g., purchased within last x months, typically opens email, geographic region, etc). Depending on how "sophisticated" the criteria are and how backed up the analyst department is, this may take a couple of days to get turned around.
- The list of addresses is created and then pruned down by known unsubscribes or other do-not-email constraints in the system at the time the query runs.
- The resulting list gets sent out for review and approval by the marketing manager and client (how many people are we going to mail, what is it going to cost, what sort of metrics do we expect, etc). Since this is a human-in-the-loop process, it may again take up to several days to turnaround.
- After approval, the list gets churned through the unsubscribe list again, dropping any new unsubs. This step should catch new unsubs within that "it may take up to few days" window mentioned in the title.
- The final list is then queued up for sending, which depending on the size and meter rate may go out over the course of several hours. If you've already been queued up your unsubscribe request is typically going to get missed for this run.
Now, add on the complexity of syncing up multiple databases between the ESP and the customer, which is typically a nightly batch job at best. So even though your unsubscribe hit some web server instantly, it may take a couple of days for it to fully filter through from the web server to the client's marketing databases into the ESP's database. It's similar to why banking and ACH is so terrible: it's just ancient design patterns and slow process and nobody wants to pay money to modernize it. And if they miss a few unsubs they are still well within the legal bounds so it's whatever.
tl;dr: A lot of email marketing still runs on chains of batch jobs which can introduce windows of unsynchronized lists getting sent out.