Control for Your Email Distribution Lists
We have previously discussed the various options for email distribution lists in our post: Three Kinds of Distribution Lists. However, we are often asked how to make distribution lists with special properties, such as:
- Only people who belong to the list can send to the list
- Have messages sent to the list be spam filtered
- Only forward messages with certain content in them to the list
- Block messages from certain people or with certain content in them
- Add custom headers to messages sent to the list
- Etc. – the list goes on
These are all very doable at LuxSci by using a “4th” way of making a distribution list — using custom email filters.
The Custom Filter Distribution List
In order to create distribution lists of arbitrary complexity, in terms of what gets accepted and what gets rejected, we follow the following basic formula for a LuxSci-hosted email account:
- Create an email alias that will be the email address to which people send email that should be delivered to the distribution list. I.e. “firstname.lastname@example.org”.
- Have that email alias forward all email sent to it to one of your administrative users (it can be any user, but usually this is done by an administrator), i.e. “email@example.com”
- Create a Custom Email Filters in the account of that administrative user.
- Each filter should be configured to match all “Messages to” the email alias email address, and possibly other criteria as well.
- The custom filters are applied in the order that you have them stacked in your account; so, use that order to determine what criteria are checked when.
- Some filters can bounce/deny messages, some could send a copy to an archival folder or address, and one or more could forward the messages to a comma-delimited list of email addresses that is the actual distribution list.
Other Features of These Distribution Lists
- Hides the recipients: None of the recipients will see the actual email addresses of any of the recipients — all they will see is the email address of the distribution list itself.
- Easy to update: You can easily update the recipients of the distribution list by editing your email filter. You can also use Groups WebAides and other techniques to make list address management simpler and visual.
- Maximum recipients: By default, distribution lists created in this way are limited to 30 recipients; however, LuxSci can increase this for you to the number of users in your account or even larger upon approval.
Example: Distribution List that only some people can send to
To create an email distribution list that can be used only by a few people for sending out messages, you would:
- Create the alias and have it forward to the user who will have access to the custom filters
- Create a custom filter that:
- Matches messages to the email alias address
- Matches messages “From” any of the allowed senders: Enter a comma-delimited list of permitted sender addresses in the “Messages from:” criteria.
- Has an action that will “Forward message to:” an “Email Address”. However, that “Email Address” will be a comma-delimited list of the email addresses that constitute the actual distribution list.
- Create another custom filter to apply after the previous one, which:
- Matches messages to the email alias address
- Has an action that either deletes the message or bounces it back to the sender
This will result in messages sent to the alias from an allowed sender being forwarded on to the list and all other messages sent to that alias being bounced/deleted.
Using this example as a basis, you could create additional rules to allow/deny forwarding based on matching message content, message size, particular headers, message subject content, and other things. You can also perform multiple actions on messages such as saving some to a folder, forwarding to an archival user or different mailing lists based on certain criteria, stripping attachments or converting messages to plain text, and even importing copies of the messages for archival in a Documents or Blog WebAide.
The only caveat with this method is that messages sent via BCC to the email alias address will not match the custom email filters that we have been created here. This can be resolved by creating additional catch-all rules for what happens if none of the above rules matches, etc. Also, if the administrative user only receives email from the list alias and nothing else (maybe its address is the alias address), then there is no need to discriminate between messages sent to the user and the distribution lists(s) — as all the messages are for the distribution lists. This configuration of having a dedicated user for the distribution list greatly simplifies email processing and the custom rules themselves.
If you have questions on how to implement your distribution list criteria in custom email filters, please contact LuxSci Support for assistance.
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