Send an email with Mozilla Thunderbird

Use Thunderbird to send a new message from a configured business mailbox. A successful send depends on the account's outgoing SMTP connection, which can fail independently even when incoming mail continues to arrive normally.

Before you start

• Complete mailbox setup and have the recipient's correct address. For cPanel mail, keep the Connect Devices settings available if outgoing authentication needs checking.
• Prepare any attachments and confirm that the recipient should receive them. For a first connection test, use a short message without files.

Instructions

1. Create a message

   Select New Message, or Write in older Thunderbird layouts. Check the From field before composing, particularly when personal and business accounts share the application.

2. Add recipients

   Enter the full destination in To and confirm each address. Use Cc for visible additional recipients or Bcc when recipient addresses should not be shared with the group.

3. Write the subject and body

   Use a subject that explains the message and add the information the recipient needs. Review suggested addresses carefully rather than relying on similar display names.

4. Attach files and send

   Add the intended files using the attachment control, then check their names and sizes. Select Send when the account, recipients and content are correct.

Check the result

• Confirm a copy appears in Sent. For a setup test, verify receipt at the destination and send a reply back; a Sent copy alone does not prove inbox delivery.

Troubleshooting

The message remains in the Outbox

Check that Thunderbird is online and review the send error. Avoid repeatedly sending duplicates while an earlier copy is still queued.

Incoming mail works but sending is rejected

Check the SMTP account assignment, complete username and mailbox password. If a small test sends but an attachment does not, review the service's message-size limit.

Watch the video

The video may show an older interface. Use the written instructions above when screen names differ.

Continue with a related task

• Set up cPanel email in Mozilla Thunderbird
• Check for new email in Mozilla Thunderbird
• Forward an email in Mozilla Thunderbird
• Reply to an email in Mozilla Thunderbird