I realise this is of interest to only a few, but it’s worth a mention.
I do bulk email marketing for clients, and when we kick off with a new “cold” email address it’s best to warm it up first. I’ve tended to do this manually in the past, but it’s got too much so I’ve looked at using a service.
I’ve tried a few, most didn’t even reply to enquiries! But WarmupInbox.com did, within the hour, then responded to follow-ups within minutes. So they have great comms.
My understanding is that most of these companies do more or less the same thing in the same way, so while the service is generally the same with them all, it’s things like comms that can make the difference. And price of course. And these guys charge $9 per month per inbox. Very reasonable.
So, if you need such a service, they are worth chatting with.