"Help! Email Failed!"

by  Sam C. Chan


October 1, 2005

This is an analysis on what could be causing the frequent and dreaded "email failed!" support calls. The light-hearted opening (borrowed from Eyeful Tower) was created as a result of numerous ISPs and IT personnel being wrongly blamed for email failures, due to user ignorance. Next time your email fails and you pick up the phone, remember this to save yourself from loss of dignity. If you're a junior consultant, read this introductory checklist and start your basic learning, before jumping to conclusions. It helps to be barking up the right tree.

If A can't talk to B and A is perfectly fine, it must be B's fault.  -Clueless in Seattle.
Dear Clueless: Have you considered it might be X, Y, Z, etc. along the way between A and B? Besides, the fact that A can talk to C is not proof that A is perfectly fine.   -Samcelot

I've tried everything and it still doesn't work. Must be your fault! -Confused in Iowa.
You're barely aware of 2% of the potential issues. How could you have tried "everything?" So, shut up and sit down! Let's get to work, shall we?    -Samcelot

For your own sake, stay blissful.
Believe me, life is not easy being in the know.
Just don't assume,
for it makes an ass- out of -u- and -me.

The Email Fairy

The email fairy advises you to NEVER ASSUME...  Eyeful Tower,  Bravo Technology Center

Email failures could be caused by numerous things. Many common items are often completely overlooked. The email process is complex, and involves more than just the sending and receiving computers plus the server. Each layer of the process is a suspect.

When email failed, the troubleshooting process is further complicated by the tendency of certain entities to over-assert their denial of fault, and recklessly point to any convenient target as a "must be" cause with unwarranted authoritative confidence. Due to the nature of compensation scheme, these calls are always treated as hot potatoes by most entities involved. They employ elaborate official responses and pseudo-scientific "proofs" to do the trick.

An experienced consultant will systematically narrow down the issues and focus on the few primary suspects for the situation at hand. He/she will instinctively know to reject certain false or illogical responses, and persist as warranted. This has to be all done within the inherent limitations of the tiered support systems at multiple organizations. The goal is to expedite escalation of the case to a properly level of specialists for effective remedies to commence. Tactfully sense the knowledge, logic and comprehension level of the tech. Politely protest any irrelevant/inappropriate procedures and tests, backed by facts and rationale; without alienating anyone.

This also illustrates the importance of streamlining the number of entities involved in the overall provision of services. Email failure troubleshooting is exponentially simpler, if you have direct control over the hosting aspect (actual server-level control, that means in-house, or co-location at data center, not just having a reseller plan), provided that you also possess the necessary advanced expertise.

A resilient and redundant system design at client site would help to ease the pressure when email failed. This in turn opens up problem solving options that are less costly and more effective. Like a good boy scout: Be Prepared! A properly and holistically designed IT infrastructure for small businesses should allow for graceful degradation of services, where a single point of failure would not create cascading and catastrophic operational failure to the business.

Key questions to define the exact extend and nature of failure:
(Must answer before troubleshooting can begin)
  • What are the exact error messages you received?
  • When was the last time it was known to be working?
  • Anything interesting done/happened since?
  • Do you have a live internet connection at this moment?
  • Does if affect all stations at your site?
  • Does if affect all users at your site?
  • Does it affect all email accounts?
  • Does it fail in sending, receiving, or both?
  • Can you receive from anyone at all?
  • Can they send you a new email, instead of reply?
  • Can you send to anyone at all (by-passing your address book)?

Here is a partial list of common potential issues: (recartovarb)
(Organized by categories, not by probability of occurrence)

  • invalid Recipient domain
  • domain name registration expired
  • unknown Recipient user
  • typo in email address (valid, existent, but incorrect domain)
  • Recipient quota exceeded
  • "address book" issues
  • invalid reply domain
  • incorrect reply address in email client
  • incorrect default account in email client
  • incorrect email address (or default entry) in Exchange Active Directory

  • destination server unreachable/non-responsive
  • local DNS hijack
  • local DNS caching
  • Recipient domain registrar issues
  • Recipient domain authoritative name server issues
  • general DNS issues, including DNS poisoning
  • SMTP server unreachable/non-responsive
  • SMTP reject, unauthorized origins (addresses)
  • SMTP reject, banned destinations
  • SMTP reject, failed authentication: incorrect login/password
  • SMTP reject, failed authorization: at wrong physical site
  • SMTP reject, wrong authentication mode
  • send size exceeded
  • send volume exceeded
  • send frequency exceeded, ISP throttling
  • Sender blacklisted by Recipient receiving server
  • Sender listed by international blacklists
  • Many blacklists are recklessly aggressive, a few are fraudulent
  • Recipient blacklisted by Sender SMTP
  • Recipient address/alias black hole(s) (by design or inadvertent)
  • Recipient domain unattended catch-all alias
  • lacking valid SPF
  • SMTP confiscates viral content, could be false positive
  • form-based/scripted HTML content triggered filtration
  • SPAM filtering at sending ISP
  • SPAM filtering at Recipient ISP
  • SPAM filtering at Recipient Exchange Server/sendmail Server/Qmail Server
  • SPAM filtering at Recipient PC
  • See also:   Exchange Server Operation Modes   |   More Articles

    External Links for email troubleshooting: Yahoo | Roadrunner | AOL |

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