Tips to fix email Error 550 in Outlook 2016, 2013 & 2010

Tips to fix email Error 550 in Outlook 2016, 2013 & 2010 1
Outlook / Microsoft

Simple Mail Transfer Protocol or SMTP server is a mail transfer server, used for sending or receiving emails from a particular domain. It is a part of the application layer of the TCP/IP protocol, and without it, the emails would not go anywhere. Due to its limitations regarding queueing and receiving mail messages most organizations use SMTP along with POP3 or IMAP. Still, if the outgoing (SMTP) server does not recognize the receiver as an authentic user, it may reject and return the email with an SMTP error 550.


Disclosure: This is a guest post and the author’s views here do not necessarily reflect those of the blog owner.

The error message is cryptic like ‘550 Requested action not taken: mailbox unavailable’ and refers to a syntactic problem or a connection error. This cryptic error code (550) by SMTP server is not just a number. Each value in the code conveys particular information:

  • First value denotes the server acceptance for the command/server run into the temporary issue/encountered an error, etc.
  • Second value denotes a connection error
  • Third value indicates a syntactic problem

Basis these values, the Administrators try to detect the exact nature of the problem and decide upon its fixes.

Email error 550 is a problem at the email recipient’s end, and hence the error is caused due to factors outside an email hosting server. But, this doesn’t mean that the problem cannot be created from the sender’s end. Verify the email and the Server settings from the sender’s end. If the issue is not resolved even after verifying the settings from the sender’s end, then look for proper software to address the issue.

See also 7 easy tricks to increase your email productivity.


Fix email Error 550 in Outlook 2016, 2013, 2010

1. Verify Email address

Ensure that the recipient’s email address is correct. It should not contain any typos or extra spaces in the address.

2. Confirm with the recipient for the correct email address

If there is no typo and there are doubts concerning email address, make a call to the recipient to confirm and verify the email address. There is a possibility that the domain name got changed, and the recipient may have shared the previous domain name.

3. Ask Admin to change the Port for Outgoing SMTP server to 26 or 465

Maximum spamming is done through Port 25. Changing the Port to 26 or 465 may stop spamming or spoofing.

4. Scan the computer system and network for virus or malicious attack

Almost all computer systems have an antivirus installed in them. However, the license may have expired, or the antivirus may have got hacked. Verify the permissions and change the password for antivirus.

5. Check if the mail server user is your ISP’s mail server

Check whether the Internet Gateway is filtering and blocking the outgoing emails. In that case, check the Internet Service Provider (ISP) Connectivity and contact ISP for assistance. The providers are the better judge for their system and services.

6. Check Firewall Rules

Sometimes Firewall rules may stop the to and fro traffic of emails. Check the Firewall Rules and make necessary changes, if required.

7. Password Policy in place

The password policy should include assigning a random mix of password that must be changed after every short interval say 90 days. Also, all organizations including small, medium and large must follow the rule of changing the passwords across the network and the critical systems, when an employee from the IT department leaves the organization. Additionally, if anything untoward happens, then it is recommended to change the password.

Though keeping a check on the system is always recommended, issues do arise! And these need to be resolved at the earliest.

Using a tool-based solution

Deploy a software such as Stellar Repair for Outlook to repair the issues related to Outlook data files.  All you have to do is to install and open the software, select a corrupt data file and click on repair. The software will scan and display a preview. You can easily verify the data file contents and save the data in the preferred format.

Once the file is repaired and saved, import the data in Outlook and start sending emails. The software helps in removing the corruption in data files and lets Microsoft Outlook users send emails in the case of SMTP Error 550.



Outlook Administrators always keep a check on the policies and procedures concerning use of the email client. Still, there are times when the users experience problems like SMTP Error 550. When all the checks are in place, then the problem erupts due to corrupt data files, which can be resolved with an Outlook repair tool like Stellar Repair for Outlook.

The software fixes the issues in three simple steps: Select Outlook data file, scan, and repair PST file in Outlook, and save the file. And all these steps are easily steered through the interactive user interface of this reliable software. The software supports all versions of Outlook including 2016, 2013, 2010 and earlier, which is an added ease when it comes to correct the email client.

This is a guest post by Rajan Singh.

Rajan Singh, a tech consultant with 5 years+ experience in RDBMS, Email, Mobile Platform & AI. He likes to write troubleshooting guides to fix Outlook email errors & repair PST file to recover lost emails using safe tricks.


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