Filter Policy

Spam filtering: the ticket generator on every account

There is no filter setting that produces no complaints, only a choice about which complaint you would rather receive.

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Straight answer first

A spam filter scores every inbound message against a set of tests and diverts or discards whatever crosses the threshold — and as a reseller your problem is that both possible errors arrive as your fault: too much rubbish in the inbox, or one important message that never appeared.

There is no setting that produces no complaints, so the real decision is which complaint you would rather receive. A loose threshold buys you weekly grumbling about rubbish in the inbox. A tight one buys you a single furious call about a quote that never appeared and a job that went somewhere else. Choose deliberately, write the choice down, and put it in the welcome pack so the client heard it from you first.

Written by the Hosting Seller staff · Checked 4 August 2026

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Cover in both directions

Filtering happens on the server before mail reaches a mailbox. The tests look at where the message came from, whether the sending domain's records line up, what the content resembles and how the sender has behaved elsewhere. The result is a score, and the score is compared against a number.

Filtering and virus scanning are fitted to every mailbox before a client logs in, which means the default is already sensible. What varies is how much a particular client's mail resembles the things the tests were built to catch.

You are blamed in both directions

Loosen the threshold and a client complains about rubbish arriving. Tighten it and a client complains that a supplier's invoice never appeared. There is no setting that produces silence, and any reseller who has run more than a dozen mailboxes already knows which of the two complaints costs more.

So make the trade deliberately rather than by inheriting a default and hoping. Err towards delivery, put the borderline mail somewhere the client can see it, and make checking that place part of what you tell them at handover.

The false positive that costs a client money

A quote from a new customer, an invoice, a job offer, a booking confirmation. Legitimate business mail gets caught for prosaic reasons: it was sent from a badly configured server, it came through a forwarder, it was one message in a burst from an address nobody had seen before.

When it happens, the client does not experience it as a technical event. They experience it as having lost a piece of work because of the hosting you sold them, and that is the framing you have to answer.

Where the threshold lives, and who should move it

It sits per account in the panel, which means it can be delegated. Whether it should be is a judgement about the client: a technically comfortable one will tune it sensibly, while a client who moves the slider to the strictest setting after one bad week will be back within a fortnight having lost something.

For most client lists, keep the threshold with you, keep it consistent across accounts, and give clients control over their own allow list instead. That gives them the lever they actually need without the one that causes harm.

What to tell a client before they ask

Two sentences at handover: unwanted mail is screened before it reaches you, and if you are expecting something that has not arrived, look in the spam folder first and tell us the sender. It costs nothing to say and it removes the first exchange from every future complaint.

Add the allow-list instruction for their accountant, their main suppliers and anybody whose mail they cannot afford to lose. Phishing and DMARC are the entries that cover the mail you actively want stopped.

The feature clients notice only when it is wrong

Mail filtering is the feature clients notice only when it is wrong, in both directions at once. These entries are written so you can set a policy and explain it in two sentences.

Spam and virus filtering is fitted to every mailbox before the client ever logs in, so the default is already a sensible one.

Both failure directions costed, not just the obvious one
A policy you can state to a client in two sentences
What to delegate to the client and what to keep on your side
Linked, so the forgery entry follows straight on

Why Hosting Seller

On every plan, as standard

Both errors given a price

Too much rubbish and one missing quote, weighed against each other rather than treated as a single problem.

The expensive false positive

The message that never appeared, the job that went elsewhere, and why the client blames you in either direction.

Where the threshold lives

Which control sits with you, which sits inside the account, and who ought to be allowed to move it.

Delegation decided in advance

The allow list handed to the client, the slider kept back, and the reasoning behind the split.

Said before it is asked

A line in the welcome pack that turns a future complaint into a conversation you have already had.

Filtering, as a stated policy

The choice, the delegation and the wording, settled once for the whole client list.

First Steps

From choosing to live

1
Choose which complaint you prefer
Decide once, across the client list, whether you would rather explain unwanted mail or a missing invoice. Every threshold decision follows from that answer.
2
Give clients the allow list, keep the slider
Let them rescue senders they care about without letting them set a threshold that will lose them work. It is the lever they need without the one that hurts.
3
Put the check in the welcome pack
Two sentences telling a new client where borderline mail goes removes the opening exchange from every filtering complaint you will ever receive.

In the Box

Packed with every plan

Spam and virus screening on every mailbox you create
Imunify360 standing over every client site
Mailboxes on the client's own domain, included rather than sold back
Webmail plus IMAP, POP and SMTP on every mailbox in every account
Daily backups taken across every client account
DDoS filtering handled out at the network edge
Free SSL on every client site, reissued before it lapses
Client accounts moved in by our staff, at no charge
Nothing charged at setup on any reseller tier
Real people answering, for you and for your clients

Across the Counter

Things people ask us all the time

A client missed an order because it was filtered. What do I say?

Acknowledge it as a real cost rather than a technical curiosity, retrieve the message, add the sender to their allow list while you are there, and explain in one sentence why it happened. What loses the client is treating a lost job as a false positive with an explanation attached instead of a problem with a fix attached.

Should clients be able to change their own filter strictness?

Usually not. A client who has just had a bad week will set it to the strictest option available and lose something important a fortnight later, then raise it with you as a fault. Keep the threshold consistent across your accounts and give them control of their own allow list instead.

Can I run one filtering policy across every account I host?

You can, and consistency is worth more than per-client tuning for most books of business. It means a complaint has one known cause, a fix you have applied before, and an explanation you have already written. Reserve custom settings for the handful of clients whose mail genuinely justifies them.

A client's own outbound mail is being filtered by recipients. Same system?

No, and the distinction matters. Inbound screening is on your platform and you can adjust it. Outbound judgement happens at the receiving end and is driven by the client's own records, their sending behaviour and the reputation of the relay they share with your other accounts. That is a deliverability job, not a filter setting.

Moving your site to another host? Start with this checklist.

A step-by-step order of work for a move your visitors never spot: which files to copy first, how to carry email across without losing one message, the right moment to repoint DNS, and the two mistakes behind nearly every hour of downtime people ring us about.

A sensible default before the first client logs in.

Spam and virus screening fitted to every mailbox you create, Imunify360 standing over every client site, and DDoS filtering handled out at the network edge.

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