Email Errors #1: 553 Needs Authentication
All email errors start with the number 4 or the number 5. The number 5 usually means that your email client is misconfigured, as in this error, which occurs only when you try to send an email.
As the message indicates, you need to authenticate, but it doesn’t tell you exactly what that means nor how you do it. Authenticating is sending your password to the email server. There’s two different occasions where you send your password: when you download email and when you upload email.
Email errors like 553 only occur when you upload (send) email. The error indicates that you aren’t sending your password when you upload email, or you’re sending the wrong password.
To fix the error, go to your email configuration tool and find the screen that deals with the Simple Mail Transfer Protocol (SMTP), sometimes called outgoing email. Look for a box that says something like “authentication” or “name and password” and make sure it’s enabled and your username and password are entered. Then save you settings and try sending email again.
Email Errors #2: Could Not Connect
This problem mostly affects people who have been using the same settings for a long time. If this problem happens to you, it most likely means that you’ve become another innocent victim of the war between system administrators and spammers.
System administrators at big Internet Service Providers (ISPs) know that many of their customer’s computers get infected with viruses and Trojans everyday, and that much of that malware ends up sending spam. Not only does spam waste the ISP’s bandwidth, but it also angers other ISPs whose customers receive that spam. So, in an attempt to reduce the harm done by spammers, your ISP decided to institute one or more of the following anti-spam measures:
* Block Port 25 which historically carried most email. To see if this might be your problem, check the SMTP or outgoing email section of your configuration screen to see if you’re using port 25. If you are, and you think this might be your problem, change the port to 587.
* Change Domain Names (also know as fully-qualified domain names [FQDN]) is something ISPs sometimes do, particularly when they rollout a new system. You probably received a notice about the change with your last few bills from your ISP, although you may not have read it. To fix this problem, you need to find out the new domain name, so get comfy and call customer support.
* Requiring SSL/TLS-Based Authentication can break older plain-text or hashed authentication. Secure Socket Layer (SSL) and Transport Layer Security (TLS) prevent hackers from discovering your password as you send it to your ISP; it can also prevent hackers from reading your email when you send it. To enable it and see if it fixes your problem, go to the SMTP or Outgoing Email section of your configuration screen and enable SSL. If SSL doesn’t work, enable TLS. If you haven’t already, you will need to enter a username and password now.
Email Errors #3: Sent Email Disappears
Did you send an important email and then discover it never reached its destination? This is another unfortunate side-effect of the war against spam: almost all ISPs today run outgoing email through a spam filter so that they don’t send spam. If they do send too much spam, other ISPs block them and none of their customers can send email.
The problem is that when your ISP scans your email for spam, sometimes it gets what’s called a “false positive”. That means a legitimate email gets flagged as spam. For example, a legitimate email about pharmaceuticals looks very similar to an illegitimate spam email. When your email gets flagged as spam, your ISP doesn’t always tell you that it didn’t deliver it. The solution to this problem is to write down the details of any emails that didn’t get through, call your ISP, and complain about not receiving rejection notices.
Email Errors #4: Username and Password Not Accepted
Email errors like this are catch-all errors for mail servers—ISPs send the error even when your username and password or correct. But you should start trying to fix these email errors by taking them at face value: check to see if your username and password are correct. Type them a few times just to make sure there are no typos and, if possible, log into your ISP’s website using the same username and password to ensure they still work.
If typos aren’t at fault, it’s possible you need to configure something before you’re allowed to send or download email. This is most often the case for GMail users. Before you can download or upload email to GMail, you need to configure Gmail for remote access. Log into the GMail website, go to the GMail settings screen, and enable POP Download and IMAP Access. I have had this problem when trying to enter my password for a Gmail Imap email in Outlook. I kept getting an error message saying web login required.
Email Errors #5: An Unknown Error Has Occurred
The most useless of all error messages, this email error is found only in Microsoft Outlook and Outlook Express. It means that your inbox has been corrupted—but don’t worry, you can usually recover all of your emails.
To fix this error, first you need to find the .pst file that stores your email. Go to Find or the Search box and enter .pst to find all .pst files. Look for the .pst file that you were trying to read when you received the email errors and write down its filename.
Next, start a new search for SCANPST.EXE. Because scanpst is outside your usual search directories, this search will take a while. When it finds scanpst, double-click it to start the .pst repair tool. Scanpst will prompt you for the name of the .pst file you found earlier—enter the name now and click Start. After it finishes running, all you need to do is restart Outlook or Outlook Express to get rid of the email errors.
David A. Harding began using Linux in 2001 and quickly became a Linux Professional Institute certified system administrator. His articles have appeared in over a dozen publications and he has given over 50 presentations about Linux—including two Software Freedom Day keynotes. Dave always loves to hear from readers at [You must be registered and logged in to see this link.]. He depends on email for his living, so he always keeps his eye out for email errors.