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How do I authenticate my SMTP server?

How do I authenticate my SMTP server?

SMTP is the protocol that allows you to send emails from your email account. It’s used for sending messages through a company-provided or third party service provider such as Microsoft Exchange Server. The SMTP protocol is also known as Simple Mail Transfer Protocol (SMPT).

An SMTP connection establishes a network session between two hosts with one host acting as a sender while another acts as a recipient of the message. Sender sends data packets over the internet using the SMTP protocol to deliver them to their intended destination.

The process involves connecting to a specific port number on a remote computer called “server” which provides this functionality. This server can be located either within the same organization or outside it. If it’s connected to the local area network (LAN), then it will act as a member of the internal domain.

If it’s not, it could belong to any other network like the Internet or corporate intranet. When we connect to these servers, they provide us with various services including hosting our web sites, storing our files, providing access to databases etc. All this happens behind the scenes without actually knowing about it. These days most companies use cloud computing solutions and therefore have no control over where exactly the servers are hosted. But before we move onto the next step, let’s understand more about the SMTP protocol itself.

How do I fix SMTP authentication error in Gmail?

When you set up your Gmail account, there was probably a section titled Settings & Accounts under the General heading. There may even be separate sections for different types of accounts like Google Apps accounts, work/personal accounts etc. You might have noticed that each type has a slightly unique name depending upon whether you had created it yourself or if it came preinstalled when you signed up for your Google account.

In case you forgot, here’s how to create a new Google account:

Click Sign In at the top right corner of the screen.

Select Create Account.

Enter all required details and click Next.

You should now see a confirmation page stating that your account information has been successfully verified. Click Continue to proceed further.

Once you log into your new Gmail account, open the settings cogwheel in the upper left hand side. Choose the Advanced tab and scroll down until you find the Email option. Here, you can change some basic features related to your emailing experience such as enabling Smart Reply, choosing your preferred language and adding custom signatures.

Scroll down again till you reach the Security Options section. Under this section, you will notice three options labeled as SSL/TLS, STARTTLS, and AUTH LOGIN. Select TLS /SSL as shown below. Then click Save Changes. Your changes will take effect immediately after you save them.

Now, go back to the main settings window and choose the Gear icon beside the From dropdown menu. Here, select More advanced settings. Scroll down to the bottom and make sure that Enable less secure apps is selected. Now, click Save Changes.

After saving the configuration changes, restart your browser and check out Gmail once again. Hopefully, you won't face any issues with the authentication process anymore!

For more detailed instructions, read How to Turn On Less Secure App Access in Chrome.

What does SMTP authentication error mean?

Before moving ahead, it would help if you know why the authentication fails. For instance, if you’re trying to send an email to someone who doesn’t own a Gmail account, the authentication might fail because Gmail requires users to verify their identity first. Let me explain this better.

As mentioned earlier, every user needs to sign into his or her account via a website provided by Google or any other third-party service provider. Once logged in, he or she receives a verification code. That code must be entered into the corresponding field during the SMTP authentication procedure so that the email gets delivered.

This kind of authentication is quite similar to logging into websites using passwords. However, unlike websites, there isn't much security involved since anyone having access to the credentials could easily impersonate someone else and send spam emails. So, you need to ensure that the credentials being used aren't compromised. This is where the concept of 2FA comes handy.

Why does SMTP authentication fail?

There are several reasons why authentication often fails. Some possible scenarios include:

Your IP address hasn’t changed recently.

A firewall is blocking outgoing connections.

Some anti-virus software installed on your system is interfering with the SMTP traffic.

Your ISP is currently experiencing technical difficulties that prevent them from delivering e-mails.

How do I authenticate SMTP?

Let’s look at a few ways in which you can configure your SMTP server properly so that it works seamlessly with your Outlook clients. Remember, you don’t necessarily need to follow everything listed below – just pick whatever suits you best!

Enable SMTP Authentication in Office 365

To start off, head over to the admin portal of your Office 365 tenant. After signing in, navigate to Admin " Communications " EWS Manageability. At the top, locate the section labeled Configure your SMTP environment.

Here, you will get to specify the following parameters:

Hostname - Enter the fully qualified domain name of the server machine which you want to receive mail from (e.g.,

Port Number - Use 465 for standard IMAP/POP3 and 587 for SMTPS/STARTTLS

User Name - Type in the full email address associated with your mailbox (

Password - Type in the correct password assigned to your mailbox (password)

Use StartTLS - Check the box to indicate that you want to encrypt your communication channel using the Transport Layer Security (TLS) protocol. Note that this feature is only available for Windows 10 Professional and Enterprise editions.

Make sure that both User Name and Password fields match the ones specified above. Also, double-check the Hostname value to confirm that it matches the hostname specified in your DNS records. Finally, hit Apply button to complete the configuration.

Enabling SMTP authentication in Exchange Online

Open the Exchange admin center console via After signing in, click on the Administration tab. Here, you will find the section named Mail Flow Management. Locate the Configuration Parameters section and click Edit.

On the resulting dialog, enter the values corresponding to the above steps carefully. Make sure that you input the exact same values for Port, Username, and Password. Once done, click OK to apply your changes.

Turn Off SMTP Authentication in Outlook

Logging into Outlook using a non-Gmail login might lead to a failure in the authentication process. To resolve this issue, follow these steps:

Head over to File " Info " Account Settings.

Navigate to the Network Tab and select Advanced.

Switch OFF the Allow Other Computers to Connect Using MyEthernetIP Address option.

Close the window once finished making the necessary changes. Restart Outlook now and try sending an email. Hopefully, it will pass smoothly this time around!

Note: You can always test the authenticity of your SMTP server by sending a simple text file containing a single line of text (i.e. Hello World!) to your email inbox.

How do I authenticate SMTP?

To authenticate SMTP, you basically need to fill in the appropriate fields in the relevant parts of the SMTP request. As far as the syntax goes, it’s very straightforward. Just keep in mind that the format varies based on the method you're using to communicate with the server.

Outlook uses the following syntax for its SMTP requests:

Authentication Required:  Username: [email protected]     Passw0rd: [email protected]

Gmail uses the following syntax:

AuthLogin: [email protected]    AuthPass:[email protected]

Exchange uses something similar to this:

SMTP_USER=[email protected],PASSWORD=yourpasswd

IMAP_USER=[email protected], PASSWORD=[email protected]

To learn more about the SMTP protocol, visit the official Wikipedia site.

If you have set up a new email account or if you want to upgrade the security of your existing account, then it is time for you to start securing your emails with SMTP (Simple Mail Transfer Protocol) Authentication.

SMTP provides users with two-factor authentication that uses both user credentials as well as a secret code sent via SMS text message. This lets others know who they’re talking to so there can be no doubt about whether someone else has access to their accounts. It also prevents anyone from impersonating them online.

Here we will discuss how to configure your own SMTP Server. You might already have one – it could be at work or school, or perhaps it belongs to a hosting provider. Or maybe you use Gmail or Outlook and want to learn more about SMTP Authentication. Whatever the case may be, this guide covers all bases, including setting up a free SMTP server using G Suite, Microsoft Office 365, Google Apps, Exchange Online or Windows Live Hotmail. We'll even show you how to test your configuration before sending any messages out!

How do I check my SMTP authentication?

The first thing you need to do when trying to get started with SMTP Authentication is verify that your recipient’s email address isn't being spoofed. To do this, you should send yourself a verification email which includes a link that only works after logging into the website with the same login details used to register your original email. If the link doesn’t work, then it means your email address was probably stolen, or somebody else registered it without permission.

You can check your SMTP settings through your web browser. Go to Settings > Accounts & Import/Export and click Send Test Email to see if your email addresses are verified. Once you find the correct email address, go back into your email app. In most apps, you can simply click on the envelope icon next to your email address. From here, select "Send Verification" option. If you don't see the option anywhere, try clicking on the gear menu button located near top right corner of the screen, followed by "Settings." Then scroll down until you reach "Accounts & Imports," where you can change your settings.

Does SMTP require authentication?

Yes, SMTP requires authentication. Because of this, many people mistakenly believe that SMTP is insecure and therefore cannot provide any level of protection against spamming attacks. However, SMTP is not inherently unsafe because it relies upon other protocols like TLS encryption and SPF records. These additional measures ensure privacy and authenticity in addition to providing strong end-to-end data integrity. The main purpose of SMTP is to relay email between servers, but it’s just one layer of defense in a complex system of digital defenses.

What does my outgoing server SMTP requires authentication mean?

Authentication refers to verifying that a sender can deliver emails to recipients. When you're creating a new email account, it's important to make sure that the domain name you choose is actually owned by you. For example, if you create an email account with, then whoever owns the domain must approve your request. They usually ask for some sort of proof such as a copy of your driver license or passport.

There are several different ways to prove ownership of a domain. Here are three options:

Verify Your Domain With Whois - This service allows you to search for information related to a given domain name. Entering a domain name into this tool generates a list of results based on various criteria, including registrar status, contact info, expiration date, etc.

Check Who Owns A's Emails - This site shows a quick snapshot of who controls each individual email address. As long as you enter the exact email address you wish to check, the site returns a brief summary of the owner's identity.

Use DNS Lookup Tools - There are tons of tools available that allow you to perform a simple lookup on a domain name. For example, you can type in "", hit Search, and wait while the page loads. On the left side of the screen, look for the section labeled, "Host Name Lookups." Scroll down until you see the entry for "". Click on the arrow icon next to Host Name Lookup, and you’ll see a list of hosts associated with that domain.

Once you've confirmed that the domain is yours, log into the email app again. Select "Options" from the dropdown box under "Email Options" on the left sidebar, and then scroll down to "Delivery Status." Make sure your delivery method is set to "Automatic Delivery Only" instead of "Everyone Else," and click Save Changes. Now whenever you compose a new email, you won't receive a notification saying the message wasn't delivered, since it will automatically be routed to your inbox once you confirm your domains' ownership.

How do I authenticate incoming SMTP server?

To prevent spammers from flooding your inbox, you must take extra precautions when receiving emails from unknown sources. One way to identify potential threats is to add a filter called SpamAssassin, which checks for suspicious content like viruses, malware, and phishing links. Another useful feature is the ability to mark emails as read immediately after reading them. This ensures that you don't accidentally miss important emails that were previously filtered due to false positives.

Incoming SMTP server authentication is another crucial step in keeping your inbox safe from unwanted spam. By enabling SSL/TLS encryption, you can ensure that the communication channel between your computer and the remote server remains private. And by adding a rule which blocks certain IP addresses, you can limit the number of times that hackers attempt to break into your machine remotely. Most modern operating systems come with built-in anti-virus software that protects you from malicious files that arrive over unencrypted connections. But if you haven't installed antivirus yet, installing something like Avast Free Antivirus ($20 per year) is a great place to begin.

However, if you really feel uncomfortable relying solely on these methods to protect your personal information, consider investing in a VPN service. Using a virtual network connection encrypts all traffic passing through it, making it nearly impossible for unauthorized parties to intercept sensitive data. While many companies charge thousands of dollars for this kind of service, there are plenty of affordable ones to choose from. ExpressVPN is among our favorites, especially considering that it supports Netflix streaming.

Finally, remember that there are always risks involved with sharing your personal information online. Even though internet security has improved dramatically in recent years, it never hurts to double-check your security settings periodically.

How do I turn on SMTP authentication in my mail client?

Many popular applications support SMTP authentication, including Apple Mail, Thunderbird, KMail, Opera Mail, Eudora, Evolution, Mozilla Firefox, Chrome, IE 10+, Safari 5+ and mobile clients. Some services offer optional features that let you specify which email addresses you would like to include in your SMTP authentication process, whereas others rely entirely on default settings.

For example, if you're using Gmail with POP3 enabled, you can either disable SMTP altogether, or you can choose to only accept authenticated messages from specific email addresses. If you prefer something less restrictive, you can opt to whitelist every single email address that's currently included in your Gmail account.

This article explains how to enable SMTP Authentication in Outlook 365, Gmail and Outlook. If you'd rather skip ahead and learn everything you need to know about securing your emails using SMTP, check out our SMTP tutorial.

You can configure the settings for sending e-mails using a specific email account or with multiple accounts (such as Gmail). This allows you to send emails from one of your domains without having to worry about IP address spoofing or even security risks that may arise if you use other methods such as POP3/IMAP4.

To avoid these issues, it’s important to be able to properly identify who is sending messages through your domain so they don't get flagged as spam. In this guide we will discuss how to set up SMTP Authentication on Exchange Server 2016, which is also known as ESMTP. We will cover all aspects of setting up SMTP Authentication including why SMTP authentication is necessary, what features it offers, and most importantly, how to make sure it works correctly!

If you have any questions regarding this article - feel free to leave them below and our team member will answer them soon.

How do I find my SMTP server authentication?

The first step is finding out where your SMTP server is located. To do this, head over to the Microsoft Office 365 Admin Center and select Mail &; Messaging > Email addresses. Next, click Addresses under Manage and then choose the email address you want to add. On the next screen, click Edit at the top right corner. Then scroll down until you see "Authentication" and select Enable. You might need to logout and login back into your admin center again after enabling SMTP Authentication.  Once enabled, you should be able to locate your SMTP server within the list provided. If not, try looking around further.

Does outgoing server require authentication?

When sending mails via Outlook, only those recipients whose primary email address has been verified against Active Directory are allowed to receive the message. The recipient needs to sign onto their mailbox, enter their credentials and approve the message before being able to view it. For example, when signing into Hotmail, users must provide their user name and password before viewing incoming messages. Similarly, users of Google Apps must verify their identity when receiving new messages sent by others.

For more information on verifying identities, read How Do I Verify My Identity When Sending Emails Using G Suite?.

Why is SMTP authentication required?

There are several benefits associated with using SMTP authentication. It ensures end-to-end encryption while ensuring the authenticity of the sender. As opposed to using an SSL certificate, SMTP requires no extra steps to ensure your messages aren't intercepted during transmission. Furthermore, it improves performance because data doesn’t have to be encrypted twice.

In addition, SMTP provides additional protection against phishing attacks and malware. Since a malicious actor would likely never know the details of the SMTP servers used by legitimate businesses, he wouldn't be able to trick people into providing his own fake credentials. Instead, the attacker would have to compromise another system and impersonate someone else to gain access to the victim’s inbox.

Lastly, since SMTP does not rely on certificates, it reduces the risk of man-in-the-middle attacks. A compromised site could easily intercept traffic between two parties and replace the contents of the communication with malicious code. With SMTP authentication, however, both parties are guaranteed that the connection was valid and there were no errors along the way.

How do I fix SMTP authentication error?

Depending upon the type of error encountered, you may experience different problems. Here are some common ones:

Invalid SMTP hostname

This usually happens due to incorrect DNS records, but sometimes it can happen simply because your ISP hasn't updated the MX record yet.

Unable to connect to SMTP server

Check if the port number was changed on your router or firewall and check if the TCP ports mentioned above are open on your computer. Also doublecheck whether the remote server supports TLS connections.

Not enough space available on disk drive

Make sure that your machine isn't running low on storage space. Check if the folder containing your old emails is empty and move those files elsewhere. Ensure that you're connected to the internet and restart your PC and mobile device.

Error 534 4.7.0 : Relay Access Denied

Your provider has disabled relaying to external hosts. Contact technical support to let them know about this issue.

543 5.1.0 Must issue STARTTLS command first

Ensure that you've configured your MTA to allow relay. Try contacting your administrator and ask him to change the configuration manually. Alternatively, contact tech support to resolve this problem.

541 5.2.0 Unable to process starttls command

Try restarting your MTA service and reconfigure it to accept relays.

533 5.3.0 Error occurred processing starttls command

This typically means that your MTA is not responding. Make sure that your antivirus software is turned off and reboot your computer. If this still occurs, consider disabling antivirus temporarily.

530 5.4.0 Cannot negotiate protocol version

It's possible that your network uses older protocols like IMAPv4 and PIPES. These protocols won't work with newer versions of Windows operating systems.

550 5.5.0 Message rejected due to failed authentication mechanism

Ensure that your MTA accepts relays and that you haven't blocked relays in your firewalls. Contact your admin to resolve this issue.

554 5.6.0 Unverified domain for authenticated user

Make sure that you're logged into your Domain Controller and that your ADMX file contains the correct values.

555 5.7.0 Host rejected

Contact your administrator to solve this problem.

556 5.8.0 Connection refused

Doublecheck that the IP of your MTA is reachable and that you're connecting to the correct port. Additionally, check that your MTA is listening on the specified port.

557 5.9.0 Connected, but unable to establish secure channel

Consider checking if relays are enabled in your MTA. Sometimes, you'll encounter this problem even though relays are enabled.

558 5.10.0 Bad handshake received from server

Either your MTA isn't accepting relays or your MTA is rejecting requests from certain domains. Consider changing your MTA's policies to accept relays. However, you should always test this functionality thoroughly before deploying it across your entire organization.

559 5.11.0 No route to destination

Some ISPs block incoming relays and prevent your MTA from communicating with the outside world. Contact your ISP to confirm whether this is happening in your case.

560 5.12.0 Couldn't validate digital signature

Your MTA may refuse to communicate with clients unless you're signed in. Ensure that you're already signed in.

561 5.13.0 Time expired waiting for response from server

Your MTAs' timeout period may have expired. Doublecheck that you're connected to the Internet and that your MTAs are working fine.

562 5.14.0 Failed to decrypt incoming plaintext stream

Ensure that you're logging into your MTA successfully. Otherwise, check whether relays are enabled and whether your MTA has the appropriate permissions.

563 5.15.0 Invalid character found in header

Ensure that your MTA is allowing relays. If you're experiencing this issue despite enabling relays, contact your administrator.

564 5.16.0 Service unavailable

Ensure that your MTA is online, the port is open, and that you're attempting to connect to the proper IP.

565 5.17.0 Command timed out

If you've checked everything carefully and nothing seems wrong, it probably means that your MTA is refusing to accept relays. Contact your admin to troubleshoot the problem.

566 5.18.0 Internal failure

Ensure that your MTA is online and that you're trying to connect to the correct IP.

567 5.19.0 User unknown

Ensure that you've entered the correct username and password when logging into your MTA.

568 5.20.0 Protocol violation

Something unexpected happened during the handshake phase. Make sure that you've enabled relays and that your MTA is accepting them.

569 5.21.0 Not implemented feature

Use the --help option to learn more about supported commands.

570 5.22.0 Command unrecognized

Make sure that you typed the exact command. Don't forget to enclose it inside quotes.

571 5.23.0 Malformed line detected

Your MTA detects malformed lines as invalid. Ensure that you're typing exactly what your MTA expects.

572 5.24.0 Requested action aborted: local operation timed out

Sometimes, your MTA refuses to continue processing requests. Usually, this happens when you attempt too many simultaneous operations. Restart your MTA and retry.

573 5.25.0 Operation now in progress

Your MTA is currently handling a request. Wait patiently.

574 5.26.0 File transfer complete

Your MTA processed the request successfully. Congratulations!

575 5.27.0 Too much output



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