Updated 2026-10-08

How to Set Up an Outgoing SMTP Server in Thunderbird

In Thunderbird, open Account Settings, select Outgoing Server (SMTP), click Add and enter Server Name smtp.bulko.io, Port 587, Connection security STARTTLS, Authentication method Normal password and your Bulko SMTP username. Then choose this server as the outgoing server for your account; Thunderbird asks for the password on the first send.

Hostsmtp.bulko.io

Port587 · 465 · 2525

EncryptionSTARTTLS · SSL

Loginfrom dashboard

Thunderbird SMTP settings

Field	Value
Description	`Bulko SMTP Relay (any label)`
Server Name	`smtp.bulko.io`
Port	`587 (or 465, or 2525)`
Connection security	`STARTTLS for 587/2525, SSL/TLS for 465`
Authentication method	`Normal password`
User Name	`Your Bulko SMTP username (smtp_xxxxxxxxxxxxxxxx)`
Password (asked on first send)	`Your Bulko SMTP password`

Step-by-step setup

Buy an SMTP package on the Bulko SMTP Relay page and copy the username and password from Dashboard -> SMTP Access.
In Thunderbird, open the application menu and choose Account Settings.
At the bottom of the left pane select Outgoing Server (SMTP) (named Outgoing Server in the newest versions) and click Add.
In the SMTP Server dialog fill in Description, Server Name smtp.bulko.io and Port 587.
Under Security and Authentication set Connection security to STARTTLS, Authentication method to Normal password and User Name to your Bulko username. Click OK.
Select your email account in the left pane and, at the bottom of its main page, choose the Bulko server in the outgoing server dropdown. If you use several identities, set it in Manage Identities for each one that should send through Bulko.
Keep the account's Email Address on a domain you control. Bulko does not receive mail, so replies still arrive in the mailbox your account reads over IMAP or POP.

Values for the SMTP Server dialog

SMTP Server dialog in Thunderbird

Description:           Bulko SMTP Relay
Server Name:           smtp.bulko.io
Port:                  587
Connection security:   STARTTLS
Authentication method: Normal password
User Name:             smtp_xxxxxxxxxxxxxxxx

Alternatives:
  Port 465  -> Connection security: SSL/TLS
  Port 2525 -> Connection security: STARTTLS

Send a test email

Write a new message from the account you configured to an address on a different provider and click Send. On the first send Thunderbird asks for the SMTP password; enter your Bulko password and tick the option to remember it in the Password Manager.

Success means the message leaves the Outbox without an error and arrives at the recipient. Thunderbird stores a copy in your account's Sent folder as usual, because saving the sent copy is done by your IMAP account, not by the SMTP server.

Troubleshooting

Problem	Fix
Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) smtp.bulko.io timed out	Your network or ISP blocks the port. Switch the port to 2525 with STARTTLS, or try 465 with SSL/TLS.
Connection error or SSL error right after clicking Send	Connection security and port do not match. Use STARTTLS with 587 or 2525, and SSL/TLS only with 465.
Authentication failed / 535	Check that Authentication method is Normal password and User Name is the smtp_ username. Remove the saved SMTP password in Settings -> Privacy & Security -> Saved Passwords and enter it again. More: https://bulko.io/en/smtp-errors/535/.
The message still goes through the old server	The identity you send from uses another outgoing server. Check the dropdown on the account page and in Manage Identities, or click Set Default on the Bulko server.
554 5.7.1 rejected	Bulko's content filter blocked the message for phishing, malware, impersonation or scam patterns. Review the content, links and attachments.
Recipients see messages in spam	Send from your own domain and verify it in Bulko so DKIM and the return-path align. Check SPF at https://bulko.io/en/validators/spf-checker/.

FAQ

Can I receive email in Thunderbird through Bulko?

No. Bulko SMTP is outgoing only and has no IMAP or POP inbox. Keep your existing incoming server; Bulko only replaces the outgoing server.

Which authentication method should I pick in Thunderbird?

Normal password. The connection is already encrypted by STARTTLS or SSL/TLS, so the password is not sent in clear text.

Can I send from my Gmail address through Bulko?

Use a From address on a domain you control. Sending as a gmail.com or other free-mail address through a third-party relay usually fails DMARC checks at the recipient.

Is Bulko suitable for personal sending from Thunderbird?

Yes, for normal correspondence and business mail. The default limit is 2,000 emails per day, and bulk sending must follow https://bulko.io/en/acceptable-use/.

How much does it cost?

Bulko SMTP is sold as one-time packages: $5 for 5,000 emails, $15 for 20,000, $30 for 50,000 or $60 for 150,000. Unused emails never expire.

Where did Outgoing Server (SMTP) go in my Thunderbird version?

It is the last entry in the left pane of Account Settings. Newer releases label it Outgoing Server; the fields in the SMTP Server dialog stay the same.

Get SMTP credentials for Thunderbird

One-time payment by card or crypto, no subscription. Unused emails never expire. 2,000 emails per day per SMTP account.

SMTP Relay 5K: $5 · 5000SMTP Relay 20K: $15 · 20000SMTP Relay 50K: $30 · 50000SMTP Relay 150K: $60 · 150000

See SMTP relay plans

What you can send: Acceptable Use Policy.