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Why are my outgoing emails not being delivered?

This is a repost taken from Middlebury’s LIS Wiki.

We are reposting it due to the significance it has regarding many questions and issues with MIIS email.  If you feel that your emails are not being delivered or received properly, please take time to read this information.

The two most important questions to answer are:

  • Are there any links/URLs in your message or signature?
  • Are there any attachments in your message?
    • If there are attachments, are any of the attachments zip files, docx, pptx, xlsx?

Read on for an overview of the email situation.

Worldwide, e-mail has ceased to be the simple system that it was. In this message, I will try to cover some of the possible situations that can cause e-mail problems.

The cause of this change is largely due to the obscene amount of spam and junk mail. A lot depends on the reputation of the sender’s and receiver’s e-mail provider. Middlebury has kept a good reputation (so you should be able to send out e-mail from your Middlebury account without problems). Other e-mail providers may have worse reputation, and thus messages coming from those providers may be blocked.

For example, the College has been receiving enormous amounts of SPAM e-mail and this has caused our e-mail system to stop working. Thus, we invested in a service (called Barracuda SPAM firewall) that blocks SPAM for us, helping us keep the entire e-mail system up and running. Close to 99% of the messages that come to our e-mail system are correctly identified and delivered accordingly. There is a small percent of cases when a legitimate message may get identified as SPAM, and such messages are blocked. In some cases, to prevent this, you can add your colleague’s e-mail addresses (joe@email.com) or entire domain (@email.com), to Barracuda’s whitelist (instructions for that are here: SPAM).

In some cases, Barracuda may quarantine a message, so you won’t receive it directly, and the sender won’t get a bounceback. Using the same instructions as above (SPAM) you can open Barracuda’s quarantine box and look for messages there. It’s possible to be notified via e-mail whenever a message goes into this quarantine. To do this, visit the Barracuda quarantine, click on Preferences then click on Quarantine Settings, and under “Quarantine Notification” set the notification interval to “daily”.

If the instructions above don’t help, you may need to ask the sender to look at the bounceback messages that they’ve received (when an e-mail gets blocked a message bounces back to the sender, providing more information).

Reasons Why A Message May Be Rejected

There are several reasons why a message may bounce / be rejected:

– if the message had an attachment that was not considered safe
– if the message had a URL that was not considered safe
– if the words in the body of the message appeared to be heavily spam-like
– if the message came from an address that was thought to be unsafe
– if the sender’s mail system was not considered safe

Steps that may be needed to resolve these problems:

The bounceback messages contain information that can tell us why the message was rejected. There are several common “keywords” that appear in the bounceback messages. The sender needs to skim through the bounceback message, looking for keywords such as the ones below. Depending on the keyword, a different action is needed (as detailed below):

– “Message content rejected” means that there was an attachment or a URL or many words in the message that were considered unsafe. Without looking at the actual message, we don’t know what was rejected. General tips include:
* removing any attachments
* changing URLs from the format http://www.website.com/page to just “website.com/page”

– “blocked using Barracuda Reputation” means that the sender OR the sender’s domain (the e-mail system that the sender is using) has been sending large amounts of SPAM, and this has been reported by multiple sources. The report was made to “Barracuda”, the service that helps us prevent SPAM. To resolve this problem, the e-mail administrators of the sender’s domain need to contact Barracuda, and an appropriate link for contacting Barracuda. The sender needs to get in touch with their e-mail provider, and forward this link to the e-mail provider.

Original Source: https://mediawiki.middlebury.edu/wiki/LIS/Blocked_Messages_-_Non-delivered_Messages_and_Similar_E-Mail_Problems#Reasons_Why_A_Message_May_Be_Rejected

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