Answers

What service should I use to send bulk email and newsletters?

Refresh sends newsletters as broadcasts: one message per subscribed contact of a topic, each with RFC 8058 one-click unsubscribe headers. It also runs A/B subject tests, sends follow-ups to non-openers, and collects subscribers through signup forms with double opt-in.

What you get

A broadcast becomes one message per contact, never a shared To list.
Bulk messages get RFC 8058 one-click unsubscribe headers, which Gmail and Yahoo require.
Each broadcast ties to a topic, so an unsubscribe removes the person from that stream and not from your invoices.
An A/B subject test sends a test share first, then sends the rest of the audience with the winning subject.
A follow-up broadcast goes to the people who did not open the first one.
Signup forms use double opt-in by default; Refresh stores no contact before the person confirms.
A bulk subdomain keeps newsletters apart from receipts. It starts at 200 messages a day and advances on clean days.

How it works

Add news.<your-domain> as its own domain, set its stream to Bulk, and publish its records.
Create a topic and collect contacts through a signup form, the API or a CSV import.
Set the postal address in Settings → Organization, so bulk mail carries the footer.
Open Broadcasts → New broadcast, select the topic, send a test, then send or schedule.

Documentation

Create a free account: 3,000 emails a month, unlimited domains, no card.