Diagnosing Mail Problems

Mail sent from a2i to a remote site

• Suppose mail sent from a2i does not reach a remote site, and does not bounce. Usually mail that cannot be transferred to a remote site will remain queued for two or three days before bouncing back. The mail queues at a2i reside on several machines, and not all machines that handle mail allow user logins. So you will find it hard to figure out if the outgoing message is in a mail queue. Send a second message to the same address, wait a few hours, and then if neither the first nor the second message has either reached or bounced back, let support@rahul.net know. (You might need to telephone the recipient to check if the email reached.)
  • Another way of figuring out whether the mail reached the remote site or not is to deliberately send mail to an invalid address at the same site. For example, if you previously sent mail to joeuser@somehost.example.com, send another message to a made-up address at the same host: no.such.user@somehost.example.com. If this message bounces back to you quickly, this tells you that your original message probably reached the remote site. (If it didn't, it would have bounced back to you by now.)
• Suppose mail sent from a2i to a remote site bounces back. Look in the bounced message carefully. It will usually tell you why the message bounced. The five most common reasons are given below, and the bounce message will usually let you distinguish between them.
  • Bad domain name: Perhaps you are sending to an email address in which the portion of the address to the right of the @ sign is not valid. Error messages seen will be similar to: 'host unknown' and 'never heard of host xxx'.
  • Bad local part: Perhaps the portion to the left of the @ sign in the destination address is not valid, e.g., the user does not exist at the remote site. Error messages will be similar to: 'no such user', 'user unknown'.
  • Bad sending address: Otherwise, perhaps the reply address you are using in outgoing mail is bad. Some sites will refuse to accept mail that shows a bad reply address. Error messages will be similar to: 'cannot route to sender', 'domain must resolve'. (NOTE: In this case it's also possible that the bounced message will never get back to you.)
  • Recipient's mailbox is full or disk quota is exceeded. Wait a day or two and try again. Error messages will be similar to 'mailbox full', 'disk quota exceeded'.
  • Bad software configuration at the remote site. Error messages will be similar to 'error 0', 'service unavailable', 'permission denied', 'mail loops back to myself', 'configuration error', 'I refuse to talk to myself'.
  Although the errors listed above are the most common, other errors can also occur, leading to mysterious error messages. In all cases try waiting a few hours and sending your message again.

Mail sent from a remote site to an a2i user

Who makes the diagnosis?

• Problem sending from a2i to a remote site: Diagnosis will be made by you or by a2i support staff.
• Problem sending from remote site to a2i: Diagnosis will be made by remote sender or by remote sender's service provider. Diagnosis will generally not be made by a2i support staff in such cases, unless the remote service provider investigates first and then contacts us for assistance.

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