Deliverability
Whether your mail reaches the inbox, which is a different question from whether it was accepted
Deliverability is whether your mail arrives where a person will see it. It is not the same as delivery: a message can be accepted by the receiving server, reported as delivered, and filed straight into the spam folder. Delivery is a protocol outcome, and deliverability is an outcome for a human.
Nobody can guarantee it, and any provider claiming to is describing delivery. What a provider can do is remove the causes you control.
What actually moves the number
Roughly in order of how much they matter:
- Consent. Mailing people who asked to hear from you produces engagement; mailing people who did not produces complaints. Nothing else on this list outweighs it. Purchased and scraped lists are the single fastest route to a ruined domain.
- List hygiene. Repeatedly mailing dead addresses signals that you are not paying attention. See bounce, suppression list and the list hygiene guide.
- Authentication. SPF, DKIM and DMARC that pass, aligned to the domain in your From address.
- Consistency. A steady volume beats a flat month followed by a million-message Tuesday. See IP warm-up.
- Content. It matters least of the five, and it is where most advice concentrates.
In Sendly
Sendly handles the parts that are mechanical: authentication records via guided DNS setup, bounce and complaint processing, automatic suppression, and per-project sending limits that keep a sudden spike from being treated as an incident.
The parts that are editorial — who is on your list, why they are on it, and what you send them — are yours, and they are the ones that decide the outcome.