When something goes wrong

Module 8: Safe and worry-free · Reading time: 10 minutes

Learning objective: After this lesson, when you have a problem logging in, sending or delivering, you can work out where it goes wrong, read an error message or bounce, and ask for help with the right details.

Key concepts: login error, IP block, SMTP error 535, sender check, daily limit, bounce, delay notification, status code x.y.z, temporary and permanent error, Diagnostic-Code

First: where does it go wrong?

A mail problem often feels like "my email isn't working". But email consists of three separate steps, and each step has its own errors:

1. Logging in: the webmail talks to your mail server over IMAP to show your mailbox.
2. Sending: the webmail hands your message to your own mail server over SMTP.
3. Delivering: your server hands the message to the recipient's server.

With steps 1 and 2, you see the error on screen straight away. With step 3, you get an email back later: a bounce. Once you know which step goes wrong, you also know where to look.

You can't log in

The image shows the message the webmail displays when the email address or password is wrong. Check these points, in this order:

• The full address. The username is your whole email address, so emma@example.com and not just emma.
• The right password. The password of the mailbox, not that of your customer account or control panel. Watch out for Caps Lock.
• The Server field. Leave it empty, unless your domain doesn't point to your mail server (lesson 1.3). A wrongly entered server name also causes an error.
• A blocked IP address. Does the webmail not load at all, but it does on your phone over 4G? Then the firewall may have blocked your IP address, usually because a device kept trying an old password (lesson 8.1). First set the right password on all your devices, then have the block lifted.

You can't send

If you can log in but can't send, the error message almost always tells you what's going on.

One more warning about the daily limit: mail that is refused because the limit has been reached is not sent automatically later. Send important messages again the next day.

Reading a bounce

If your server can't deliver a message, you get an email back from Mail Delivery System or MAILER-DAEMON, with a subject such as "Mail delivery failed" or "Undelivered Mail Returned to Sender". A bounce consists of three parts, and you mainly need the middle one.

1. A text for people: what failed and for which address.
2. A part for programs, the delivery status notification (DSN, RFC 3464), with fixed fields.
3. The headers of your own message, so you can see which email it was.

The middle part looks like this:

Action: failed
Final-Recipient: rfc822;info@example.org
Status: 5.2.2
Remote-MTA: dns; mail.example.org
Diagnostic-Code: smtp; 552 5.2.2 <info@example.org>: Mailbox full, quota exceeded

• Action tells you whether it failed (failed) or is still being tried (delayed).
• Final-Recipient is the address in question.
• Status is the status code in the form x.y.z.
• Remote-MTA is the recipient's server that gave the answer.
• Diagnostic-Code is that server's literal answer. Always read this line: it contains the real reason, often in plain words.

Temporary or permanent: the first digit

The status code (RFC 3463) starts with a 2, 4 or 5. The same goes for the three digits of the SMTP reply code (RFC 5321), such as 550 or 452.

• 4.x.x is temporary. The recipient's server says: not now, try again later. Your own server keeps the message and tries again by itself, usually for a few days. At most you get a delay notification (Action: delayed, often with Will-Retry-Until). Don't send the message again, or the recipient will end up getting it twice.
• 5.x.x is permanent. The server gives up. Sending it again without changing anything is pointless.

The middle number tells you where the problem is. Three codes you see often:

If you get a bounce, you usually choose from four causes: the address does not exist, the recipient's mailbox is full, the receiving server refuses the mail for policy or spam reasons, or there is no connection to the receiving server. And you do one of three things: check the address and send the message again to the right address, send nothing again and wait, because the server is still trying by itself, or have something changed in your own mail or domain and ask your provider for help.

Two examples. Emma emails Ahmed (ahmed@example.net) and gets a bounce with Status: 5.7.1. The Diagnostic-Code says that Ahmed's server refuses the mail because the SPF check for example.com fails. Permanent, and refused for policy reasons: sending it again won't help. Something needs to be changed in her domain, and she asks her provider for help with that. A day after sending, Tom gets a delay notification with Action: delayed, Status: 4.4.1 and "Connection timed out" for a supplier's server. Temporary, no connection: he sends nothing again, because his server keeps trying by itself until the time in Will-Retry-Until. If he wants to be sure, he calls the supplier to say his email is on its way.

It can also work the other way round: if other people get "Mailbox full" or "Quota exceeded" when emailing you, your mailbox is full. Clear it out (lesson 5.4) and then ask them to try again.

Asking for help without back and forth

If you can't sort it out, your mail provider can help you faster if you include the right details straight away:

• the email address in question, and the recipient's address;
• the date and time, as precisely as possible;
• the exact error message: a screenshot or the whole bounce, not "it doesn't work";
• what you've already tried, and whether it's the same in the webmail and in your email program.

Never include your password. A trustworthy helpdesk won't ask for it.

In practice: how it works in the webmail

The webmail shows error messages for logging in and sending at the bottom right of the screen. A bounce arrives as a normal email in your Inbox; with Headers above the message or More > Show source, you can also see the machine part and your own headers. The Roundcube manual (chapter 13) explains what to do for each error message, and the Error messages manual goes deeper into the codes. Other webmail works in a similar way: the messages have different names there, but the codes in bounces are the same everywhere.

Summary

• First identify the step: logging in (IMAP), sending (SMTP) or delivering (bounce).
• Logging in: full address, mailbox password, Server field, and a possible IP block.
• Sending: 535 is a login error when sending, "can not send emails from" is the sender check, and the daily limit applies to your whole package.
• In a bounce, read Action, Status and above all Diagnostic-Code; 4.x.x is temporary (the server tries again by itself), 5.x.x is permanent.
• Ask for help with the address, time and exact error message, and never with your password.

Quiz

Exercise

Exercise A8.4: Reading an error message. Open the materials bounce-1.txt and bounce-2.txt (two real but anonymised error messages). For each bounce, fill in the status code, in the form x.y.z. Then, for each bounce, choose the cause from the four causes in this lesson (the address does not exist; the recipient's mailbox is full; the receiving server refuses the mail for policy or spam reasons; there is no connection to the receiving server) and what you do from the three options (check the address and send it again to the right address; send nothing again and wait, because the server is still trying by itself; have something changed in your own mail or domain and ask your provider for help). The program compares your six answers with the answer key: the status code must be exactly right (spaces don't count), the cause and action are choices. Green if everything is right, orange if something is wrong for only one bounce, red if something is wrong for both bounces. Tip: read the lines Action, Status and Diagnostic-Code.

Further reading

Where steps in the webmail are described, they apply to the WebOké webmail; other webmail works in a similar way.

• Roundcube Webmail 13.1: Can't log in
• Roundcube Webmail 13.2: SMTP error 535 when sending
• Roundcube Webmail 13.3: Your mailbox is full
• Roundcube Webmail 13.4: The daily limit has been reached
• Roundcube Webmail 13.5: Other errors when sending
• Mail delivery failed: how to read the error message and what the codes mean
• Error messages solved 1.1: Error code 550: which variant do you have and what should you do?
• Error messages solved 1.8: Account ... can not send emails from ...
• Free course Email in order: setting up and making sure it arrives properly 6.1: Reading a bounce
• RFC 3463, Enhanced Mail System Status Codes: https://www.rfc-editor.org/rfc/rfc3463