- 550 Please Turn On SMTP Authentication Error: Fix Email Sending (Outlook, Mac Mail) | Hosticko
- Table of Contents
- What the 550 please turn on SMTP authentication error means
- Quick Fix: Enable SMTP authentication
- Fix in Outlook (most common)
- Fix in Apple Mail (Mac)
- Use the correct SMTP port + encryption (587/465)
- Other causes: DNS, Email Routing, SPF
- What to send Hosticko Support
- Related Hosticko guides
- FAQs
550 Please Turn On SMTP Authentication Error: Fix Email Sending (Outlook, Mac Mail) | Hosticko #
550 please turn on SMTP authentication means your email was rejected because your mail client (most commonly Outlook)
is trying to send without proper SMTP login (authentication), or your domain/mail routing is mismatched after a migration.
This guide shows the exact fixes that usually resolve it fast.
If you want us to check your exact sending logs and settings, submit a ticket:
https://client.hosticko.com/submitticket.php
What the 550 please turn on SMTP authentication error means #
This error happens when the server expects you to authenticate (log in) before sending email, but your email app is not authenticating correctly.
Many hosting mail servers require authenticated SMTP to prevent abuse and protect deliverability.
Quick Fix: Enable SMTP authentication #
In most cases, the fix is simple: enable SMTP authentication and ensure your outgoing server uses the
same username/password as your incoming server.
- SMTP authentication: ON
- Username: full email address (example:
info@yourdomain.com) - Password: mailbox password (update it everywhere if you recently changed it)
Fix in Outlook (most common) #
Outlook 2010 / 2013 / 2016 / 2019 / Microsoft 365 (Classic Outlook) #
- Open Outlook → click File.
- Click Account Settings → Account Settings.
- Select your email account → click Change (or Repair / Edit).
- Click More Settings.
- Open the Outgoing Server tab.
- Tick: My outgoing server (SMTP) requires authentication.
- Select: Use same settings as my incoming mail server.
- Save → run Test Account Settings → try sending again.
New Outlook / Outlook on the web #
If you’re using the new Outlook experience, the UI is different and manual SMTP toggles may not appear the same way.
The fastest path is usually: remove the account and re-add it with manual settings using the correct ports listed below.
If your mailbox is a custom domain mailbox, use the Hosticko server settings (or contact Support for the exact hostname).
If you recently changed the mailbox password in cPanel, you MUST update that password in Outlook too, otherwise you’ll keep getting blocks and login prompts.
Fix in Apple Mail (Mac) #
- Open Mail on your Mac.
- Go to Mail → Settings (or Preferences on older macOS).
- Click Accounts → select the mailbox.
- Find Outgoing Mail Server (SMTP) → choose Edit SMTP Server List.
- Ensure Authentication is set to Password.
- Username should be the full email address and password should be the mailbox password.
- Save changes → try sending again.
Use the correct SMTP port + encryption (587/465) #
If SMTP authentication is enabled and you still see the error, the next most common cause is wrong port/encryption.
Use these Hosticko-safe defaults:
- SMTP (recommended): Port 587 with STARTTLS + SMTP authentication ON
- SMTP (alternative): Port 465 with SSL/TLS + SMTP authentication ON
Do not use “None/Unencrypted” unless you are testing on a trusted network (not recommended for real use).
Other causes: DNS, Email Routing, SPF #
1) MX records not updated after migration #
If your domain moved hosting/email recently, your DNS might still point email (MX) to the old server.
That can cause sending/auth issues and rejections. Confirm your MX records match where your email is actually hosted.
2) Email Routing mismatch (Local vs Remote) #
If your domain uses Google Workspace or Microsoft 365 for email, your hosting panel may need
Remote Mail Exchanger (not Local). If this is wrong, mail flow can behave unpredictably.
3) SPF not authorizing the real sender #
If you send using third-party mail services (Google/Microsoft/CRM/newsletter tools), your SPF must include them.
Otherwise some mail systems treat mail as unauthenticated and increase filtering risk.
If you tell us your domain + sending method (Outlook, website form, Google Workspace, etc.), we’ll confirm the correct routing/SPF setup.
Submit a ticket: https://client.hosticko.com/submitticket.php
What to send Hosticko Support #
To resolve this quickly, include the following in your ticket:
- The full error text (copy/paste) and when it happens
- Which app you’re using (Outlook version / Mac Mail / phone)
- Your outgoing server settings (SMTP server, port, encryption)
- Whether SMTP authentication is enabled
- Any recent changes (password reset, domain migration, DNS changes)
FAQs #
Why does port 587 matter for SMTP authentication? #
Port 587 is the standard “message submission” port commonly used for authenticated sending (with STARTTLS).
It works in Webmail, but fails in Outlook. Why? #
Webmail is already authenticated by login. Outlook must be configured to authenticate to SMTP, and must use correct port/encryption.
Can antivirus or a network firewall cause this? #
Yes. Some networks block SMTP ports or intercept TLS. Try port 587 first, then 465, or test on another network.
