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Mailpuff and PostShiba: Setup, Warm-up and Bounces FAQ
Answers about sending Mailpuff email through PostShiba: connecting with an API key, verifying your domain, warm-up, sending speed and limits, bounces and complaints, account approval and staging sites.
PostShiba is the email delivery service built into Mailpuff. You connect it once with an API key and Team ID in Mailpuff, Settings, Sending. After that, Mailpuff sends your campaigns through it, checks your domain’s DNS records, warms up a new domain, keeps within your plan’s limits, and stops mailing addresses that bounce or complain. These are the questions people ask most.
What is PostShiba?
PostShiba is a sending service made for newsletters. Mailpuff talks to its API directly, so you don’t need an SMTP plugin, and bounces, spam complaints and unsubscribes come back to Mailpuff on their own.
How do I connect PostShiba to Mailpuff?
- In PostShiba, open the API keys page and make a Full access key. Note your Team ID on the same page.
- In WordPress, go to Mailpuff → Settings → Sending.
- Paste the API key and Team ID into the PostShiba card and click Connect.
Mailpuff reads your plan’s limits and your sending domains, and sets up the bounce and complaint webhook for you. The Get an API key link on the card opens the right PostShiba page.
How do I verify my sending domain?
Mailpuff lists the DNS records PostShiba needs for the domain of your From address. Add them where you manage your domain’s DNS, such as your registrar or Cloudflare. Mailpuff checks them again when you open Settings, or you can ask for a check right away. Publish a DMARC record too: Gmail and Yahoo expect one from anyone sending in bulk, and Mailpuff’s send checklist reminds you.
A campaign can only go out through PostShiba once the domain of its From address is verified there.
What is warm-up and do I need it?
Warm-up protects a new sending domain. It starts at 50 emails a day and grows over 14 days to your plan’s daily limit, so inbox providers learn to trust the domain bit by bit. It starts on its own for each new sending domain. If your domain already has a good sending history, you can turn warm-up off on the Sending page.
A campaign larger than the day’s limit doesn’t fail. It pauses at the limit and goes on the next day, and its progress shows the expected finish.
How fast does Mailpuff send through PostShiba?
The first emails leave the moment you click Send, and the rest go in small batches in the background: 10 emails every 5 seconds unless you change it in Settings, Sending, and never more than 4 a second. Campaigns stay 10% under your plan’s hourly and daily limits, so your test emails and confirmation emails still get through. You can set your own Emails per hour limit instead.
What happens when an email bounces or is marked as spam?
PostShiba tells Mailpuff through a signed webhook, and Mailpuff acts at once:
| PostShiba reports | Mailpuff does |
|---|---|
| A hard bounce | Marks the subscriber bounced and never emails the address again |
| A spam complaint | Marks the subscriber complained and never emails the address again |
| A soft bounce | Counts it. Three within a month stop mail like a hard bounce |
| An unsubscribe | Unsubscribes the person |
A send also pauses itself when more than 2% of its addresses bounce or more than 0.08% complain after the first 100 emails, so an old list can’t hurt your domain.
Why do my emails only reach my own team at first?
PostShiba checks each new account by hand before it sends to anyone. Until it approves yours, email only reaches the people on your own PostShiba team, which is enough to send yourself tests. Once approved, your campaigns reach everyone.
Do confirmation emails go through PostShiba too?
Yes. Everything Mailpuff sends goes through PostShiba once it is connected: campaigns, tests, confirmation and welcome emails. If your PostShiba team has a separate cluster for transactional email, confirmation emails use it, so they arrive fast even while a big campaign is going out.
Is my PostShiba key safe?
Mailpuff stores the key on your site and never shows it again: the settings page shows only its last four characters, and exports leave it out. You can also put it in wp-config.php as MAILPUFF_POSTSHIBA_API_KEY and MAILPUFF_POSTSHIBA_TEAM_ID, which then win over the settings page. Disconnect forgets the key and removes the webhook.
What happens when I copy my site to staging?
A copy of your site on another address can’t send through your PostShiba account. Mailpuff notices the new address and waits until you connect PostShiba again on that copy, so a staging site never emails your real list by mistake.
Can I use Mailpuff without PostShiba?
Yes. Install the free Mailyard plugin to send through Amazon SES, Postmark, Resend, Brevo, Mailgun or any SMTP server, or keep the SMTP plugin you already use. Your host’s mail works as a last resort. The sending services guide compares every route.
Can an AI agent set up PostShiba?
Yes. An agent can connect PostShiba, check your domain, turn warm-up on or off and send a delivery test. With Saddle, connecting, changing warm-up and the delivery test each ask for your approval first. See AI agent permissions and safe sending.