Multi-step flows that go out from your own domain, thread properly, and stop the instant someone replies or opts out. The unsubscribe isn't decoration in the footer. Every message has to pass one checkpoint, and that's where it's honoured.
Flows run per job rather than per contact list, so the same person can hear from you again about a genuinely different role.
When a run starts it takes a copy of the steps it's going to send. Change the flow afterwards and your next run picks that up, while the one already in flight carries on as the people in it were promised.
Either from a mailbox you've connected or from your own verified domain. Replies come back to your inbox and thread onto the original message instead of turning up as a stray new email.
Every message goes out through one checkpoint, and that's where the opt-out list gets checked and the unsubscribe link gets added. If someone has opted out, the message doesn't go and the whole sequence stops for them. There's no way to build around it.
Ten invites a day and fifty a week from one account, spaced a minute or two apart rather than fired off together. Invites lapse after two weeks, and one that has failed for good never comes back to eat into the next day's allowance.
The caps are low on purpose.
They sit well under what the channel will actually tolerate, because getting your account restricted costs you far more than a few extra invites a day are worth.
Two flows can be rewritten but never deleted.
Every account starts with two. Rename them, rewrite them, but you can't remove them, so there's always something working to fall back on.
Opting out isn't all-or-nothing.
Someone can turn down one job without disappearing from every future conversation, and that choice is checked when the message goes out, not just filed somewhere.
Free to try. No credit card, and no credit spent until you ask for work.