Previewing Emails in Thunderbird and Apple Mail
Connect a real client over IMAP to see how multipart emails render outside the browser. Host, port, and login settings for any client.
The message view shows what arrived. A real client shows what your users see - its own HTML rendering, image blocking, font substitution. Any IMAP client connects to the sandbox like a normal mail server.
Settings
| Protocol | Host | Port | Security |
|---|---|---|---|
| IMAP | imap.smtp.dev | 993 | SSL |
| SMTP | send.smtp.dev | 587 | TLS |
Username is the full address, password is the account password. POP3 and the unencrypted fallback are there too.
Thunderbird
Open Account Settings → Account Actions → Add Mail Account
Enter the account's address and password, then choose Configure manually
Set incoming to IMAP, imap.smtp.dev, port 993, SSL/TLS
Set outgoing to send.smtp.dev, port 587, STARTTLS, both usernames the full address
Apple Mail
Open Mail → Add Account → Other Mail Account
Enter the account's address and password
When prompted for servers, enter imap.smtp.dev as incoming and send.smtp.dev as outgoing
What to Check
- Both parts of a multipart message: Thunderbird's View → Message Body As switches between HTML and plain text.
- Images blocked: clients block remote images by default - the email should still make sense without them.
- Replies: sending from the client works, but only to addresses that exist as sandbox accounts.
No client install: webmail.smtp.dev gives the same IMAP view in the browser.
E2E Flows
A Playwright test that triggers a reset, polls the API for the email, extracts the link, and finishes the flow. Same pattern for signup confirmations.
AI Agents
Give an agent a fresh address per run, read OTP codes and confirmation links over the REST API, and keep agent mail out of real inboxes.