Recommended mail configuration (prevent junk mail - conserve disk space!)

[Matt]

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Though parts of this post/thread may be relevant, the original post was made for cPanel 10, so not all of the information you find here may be accurate. This post has been left here for reference purposes only.
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This is the recommended mail configuration for optimal server performance, disk space conservation, and spam prevention.

Default address:
The default address is disabled and set to :fail: for all shared hosting customers, so this has been done for you.

Resellers have the default address option enabled. We recommend you disable it from your feature manager so that your new accounts are setup to :fail" automatically, then they cannot be edited by your users.

The default setting for new accounts is:
:fail: no such address here.

This will bounce all improperly addressed emails back to the sender, instead of delivering it to the default inbox, which is usually never used. Disabling this feature in the feature manager assures that your end-users cannot change this setting. :fail: tells the server to bounce the email, "no such address here" is sent in the bounce so the sender knows that they have sent the email to an invalid address.

Spam Prevention via Spam Assassin:
We recommend you enable spam assassin, but keep the spam box, disabled. You should use the configuration wizard and set the threshold to 5 as a starting point, and have spam assassin rewrite your subject lines for mail tagged as spam. We recommend you you give it 1 or or 2 weeks where you can adjust the spam threshold higher or lower to "tune" the filter to your preferred level. This helps you avoid "false-positives," which means mail tagged as spam, but is not really spam. False positives can occur if your spam threshold is set too low. Once you have a comfortable spam threshold, you can now configure your mail server to delete these emails as they arrive, instead of delivering them to you.

1. To automatically filter and delete email tagged as spam, click on the mail filters option in cPanel, under the mail icon.

2. Click "add filter" then read the "hint" for Spam Assassin, then apply it. This will delete all mails flagged as spam.

You will see a considerable reduction in Spam to your inbox, and you will also see that you have eliminated a lot of wasted space taken up by junk mail.

Need more? Try this one on Mail Forwarding

[kengele]

I am confused by the wording here and in the Spam Assassin section of the Control Panel -

In Spam Assassin it says "(Note: 5 is the default setting. The higher the number, the more conservative the setting.)" - "conservative" could mean either not strong or strong in this case - it is ambiguous! - Which is it?

In this article you write - "False positives can occur if your spam threshold is set too low." I assume this means if my Spam threshold is low - say "3" - I am more likely to get more mail being marked as spam. Is that correct?

I am asking because it would make more sense to me that the higher the number the stronger the setting, and therefore if I chose say "7" I would get more mail marked as spam, but from what you have written it seems that is not the case, correct?

Sorry if this sounds dumb, but to me it is unclear.

[GlowAlex]

Hi Kengele,

The threshold value determines the maximum message spamscore which spamassassin can allow. The higher the spam score rate is, the higher is the chance that once the mail has been sent, it will be filtered out as spam. So the lower the threshold value the more conservative the system is, in other words it will filter more messages.

For example we have 15 messages in a mailbox, according to the different threshold values the system will work in different ways:

Threshold: 2
Messages filtered (marked as spam): 8

Threshold: 4
Messages filtered (marked as spam): 5

Threshold: 10
Messages filtered (marked as spam): 1

I am confused by the wording here and in the Spam Assassin section of the Control Panel -

In Spam Assassin it says "(Note: 5 is the default setting. The higher the number, the more conservative the setting.)" - "conservative" could mean either not strong or strong in this case - it is ambiguous! - Which is it?

In this article you write - "False positives can occur if your spam threshold is set too low." I assume this means if my Spam threshold is low - say "3" - I am more likely to get more mail being marked as spam. Is that correct?

I am asking because it would make more sense to me that the higher the number the stronger the setting, and therefore if I chose say "7" I would get more mail marked as spam, but from what you have written it seems that is not the case, correct?

Sorry if this sounds dumb, but to me it is unclear.

[kengele]

Hi Alex,
Many thanks for the clarification. FYI your examples were very clear and useful. However I still think your 2 sentences contradict eachother, but, never mind your examples are great.

"The higher the spam score rate is, the higher is the chance that once the mail has been sent, it will be filtered out as spam. " to me means higher spam score e.g 10 = high , the higher it will be filtered out as spam, or labelled "spam" and could be deleted and not sent.

This sentence contradicts this one -

"So the lower the threshold value the more conservative the system is, in other words it will filter more messages." to me means a low score eg 1 = low, so a setting of 1 would filter more messages, so more messages would be labelled "spam" and could be deleted and not sent.

Do spam score rate and threshold value mean the opposite ????

Anyway, as I said, your examples are great. Thank you.

[GlowAlex]

They don't mean the opposite, threshold is limit (critical value) for spamscore.

For example, you have a message with spamscore 8.
With threshold set to 5 this message will be considered as spam because its spamscore is greater than the threshold, if the threshold is 10 the message will be considered as not spam because the spamscore is lower than the threshold. So spamassassin will allow only the messages with spamscore lower than the threshold.

Hi Alex,
Many thanks for the clarification. FYI your examples were very clear and useful. However I still think your 2 sentences contradict eachother, but, never mind your examples are great.

"The higher the spam score rate is, the higher is the chance that once the mail has been sent, it will be filtered out as spam. " to me means higher spam score e.g 10 = high , the higher it will be filtered out as spam, or labelled "spam" and could be deleted and not sent.

This sentence contradicts this one -

"So the lower the threshold value the more conservative the system is, in other words it will filter more messages." to me means a low score eg 1 = low, so a setting of 1 would filter more messages, so more messages would be labelled "spam" and could be deleted and not sent.

Do spam score rate and threshold value mean the opposite ????

Anyway, as I said, your examples are great. Thank you.

[kengele]

Thank you for the clarification.

[GlowAlex]

You are welcome