--- title: "Turning on SMTP Authentication" source: "https://docs.nexcess.com/hosting/email/turning-on-smtp-authentication/" description: "Configuring email on desktop or mobile can be complex due to various settings. This article focuses on resolving SMTP authentication issues." vertical: "Hosting" date: "2024-03-04" last_modified: "2026-08-04" --- # Turning on SMTP Authentication Setting up email on your desktop mail client or mobile device is tricky because there are many different settings and options. This article will cover troubleshooting a common problem: SMTP authentication. [Explore email hosting solutions](https://www.liquidweb.com/premium-email-hosting/) ## SMTP Authentication Error SMTP authentication means a username and password are required to send email. This is your email username and password. If you don’t have SMTP authentication turned on, you won’t be able to send email but you will be able to receive email. When you try to send email, your email will bounce back with an error message in the body of the email. The error will look like: ``` SMTP error from remote mail server after RCPT TO:: 550-Please turn on SMTP Authentication in your mail client. host.mysite.com 550-[123.123.123.123]:41130 is not permitted to relay through this server 550 without authentication. ``` This is an easy problem to solve by turning on SMTP authentication. In general, you’ll open your mail client and then open the email account settings and ensure SMTP authentication is turned on. Each email client does this slightly differently: - [Outlook](#Outlook) - [Mozilla Thunderbird](#TBird) - [Mac Mail](#MacMail) - [iPhone](#iPhone) - [Android](#Android) ## SMTP Authentication in Outlook 1. Open Outlook, click the **File** tab and then click **Account Settings**. In the **Account Settings** dropdown menu, click on **Account Settings**. ![Outlook account settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_r7NVHu.gif) 2. You’ll see a list of all the email accounts you have configured in Outlook. Double click on the email address that won’t allow you to send email and then click **Open**. This will open the email account settings. (You can also click **Change** above the list of email addresses.) ![email account listing](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_ZaUW2L.png) 3. Click **More Settings…** at the bottom of the account settings window. 4. Click on the **Outgoing Server** tab and check the box next to **My outgoing server (SMTP) requires authentication**. 5. Then, select the radio button next to **Use the same settings as my incoming mail server**. 6. Click **OK** to save those settings, and then click **Next** to test your settings. ![choosing and saving settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_N1USYf.gif) 7. When you see a success message, you should be able to send email without any issues. Test this by sending a test email to a different email address. ## SMTP Authentication in Mozilla Thunderbird 1. Open Mozilla Thunderbird, then click on the ![hamburger](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_GXSLxT.png) icon in the upper right hand side of the window to open the Thunderbird menu. 2. In the Thunderbird menu, go to **Preferences** and then click on **Account Settings**. This will open all the email account settings. ![account settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_wPknzF.png) 3. Click on **Outgoing Server (SMTP)** in the left navigation menu. Then click on the mailserver used by your affected email address and click **Edit…**. 4. In the **Security and Authentication** section, make sure the **Authentication method** is set to **Normal password**. This will use your email password to authenticate SMTP. ![choosing your settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_6DtJPa.gif) 5. Click **OK** to save your settings and then **OK** again to return to your mailbox. 6. Send a test email to make sure you are able to send email: you should be all set! ## SMTP Authentication in Mac Mail 1. Open Mail, click on the **Mail** menu, and then choose **Preferences**. 2. Click on **Accounts** and then choose the email account that won’t send email from the left navigation menu. ![selecting your account](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_Shu7bf.gif) 3. Make a note of the **Outgoing Mail Server (SMTP)** setting (you’ll need it soon). 4. Click the dropdown menu for **Outgoing Mail Server (SMTP)** and then select **Edit SMTP Server List…**. ![editing SMTP list](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_hLFyUb.gif) 5. Click on the server name that matches the outgoing mail server you saw in step 3. You’ll see the server information populate in the bottom half of the settings window. Above the server information, click on the **Advanced** tab. ![advanced server settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_LUhEPe.png) 6. In the **Authentication** dropdown menu, set the authentication method to **Password**. Underneath the **Authentication** field, click the check box to turn on **Allow insecure authentication**. (This doesn’t make your mail insecure, but it allows you to send email if you haven’t purchased an SSL certificate). ![authentication settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_j2Rqdh.gif) 7. Click **OK** to save your mailserver settings. 8. Close out of the Accounts window. You should be able to send email with no problem! Send a test email to make sure everything is working correctly. ## SMTP Authentication on iPhones and iPads 1. Open the **Settings** app on your phone. Tap on **Mail, Contacts, Calendars** and then tap on the account that won’t allow you to send mail. ![iPhone settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_qovsNl.png) 2. Scroll down to **Outgoing Mail Server** and tap **SMTP**. ![SMTP settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_GrtXo9.png) 3. Tap the server listed under **Primary Server** to open your mailserver settings. ![opening your mailserver settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_c9Tvtq.png) 4. Tap on **Authentication** and make sure the authentication method is set to **Password**. ![enabling password authentication](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_0UcVz7.gif) 5. To save your settings, tap **Back**, then **Done**, and then **Save**. 6. You should be able to open the Mail app and send email. Try sending a test email to make sure everything works. ## SMTP Authentication on Android Devices 1. Open the **Email** app on your Android device. 2. Tap **More** and then tap **Settings**. 3. Tap the email address that isn’t able to send email to open the specific account settings. ![Android settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_ttdca5.png) 4. Scroll all the way down to **Advanced settings** and tap on **Server settings**. ![server settings](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_nlB3fZ.png) 5. Within the **Server settings**, scroll down to **Outgoing server** and make sure the box for **Authentication required before sending emails** is checked. ![forcing authentication](https://docs.nexcess.com/wp-content/uploads/2026/06/help.liquidweb.com_Vmj22L.gif) 6. Save your settings by tapping **Done**. 7. You should now be able to send email from your Email app. Send a test email to make sure everything is working.