[DEV]

Use IMAP for reading email and authenticated SMTP for sending it. Both connections need the full mailbox address and a certificate matching the mail hostname.

Lab verification: mail.adminslab.com presented a trusted matching certificate on IMAP 993 and SMTP STARTTLS 587. Roundcube successfully accessed the mailbox and sent mail. This guide gives manual connection values for an email client; a specific Outlook or Thunderbird desktop installation has not been tested here.

1. Prepare the mailbox and hostname
Complete mail-domain DNS, mailbox creation and mail-service SSL first. Your mail hostname should resolve directly to the mail VPS. For Cloudflare, keep the mail A record DNS only. The webmail website address and aaPanel administration port are different services.

Open Mail Server → Mailboxes. Locate the account and confirm Status is enabled. The Login info column has a Copy link in our tested version. Treat copied login details as private: they can include the mailbox password. Do not paste them into a public support post.

2. Enter incoming IMAP settings
Choose manual configuration in your client and use:

• Protocol: IMAP
  
• Server: your certificate-covered mail hostname, for example mail.example.com
  
• Port: 993
  
• Connection security: SSL/TLS
  
• Username: full mailbox address, for example [email protected]
  
• Password: that mailbox's password
  

Choose the client's ordinary password authentication over the encrypted connection. Do not use the VPS root password, panel credentials or aaPanel.com account.

3. Enter outgoing SMTP settings

• Server: the same verified mail hostname
  
• Port: 587
  
• Connection security: STARTTLS
  
• Authentication: required, using the mailbox username and password
  

STARTTLS upgrades this SMTP connection to encryption; it is not the same setting as implicit SSL/TLS on port 465. Use 465 only when your own configuration confirms that endpoint is enabled. Port 25 is principally used for server-to-server delivery and is not the recommended authenticated client setting here.

4. Test both directions
Finish setup, open Inbox and compare a known message with webmail. Send a unique-subject test to an address you control. Check Sent and the actual recipient's Inbox and Junk. Reply from the external recipient and verify the response arrives. This last step checks external inbound delivery; that direction still needs a separate real-provider test in our lab.


Reference: our working Roundcube mailbox. This image shows webmail, not desktop-client setup screens.

5. Troubleshoot by symptom

• Certificate mismatch: use the certificate-covered hostname and check mail-service SSL deployment. Do not accept a mismatched certificate as the normal fix.
  
• Connection timeout: verify DNS, the intended port and both VPS/provider firewall rules.
  
• Login rejected: check the full address, mailbox password and enabled Status.
  
• Can read but cannot send: check SMTP authentication and STARTTLS 587 rather than changing IMAP settings.
  
• Message appears in Sent but not at the recipient: inspect delivery logs and the queue.
  

References: aaPanel mail protocol and port documentation · Mail-service SSL guide