We are using several advanced techniques to protect you from unwanted mass mail and spam. Our servers are attacked by many thousand bad emails per day.

1. Sender Address and IP

The sender of the email must use a machine that has a IP-Address that is resolvable to a name. If it is not resolvable, we will not accept it. That may be a temporary problem. That is why we just reject those mails with a temporary error. You have some time to fix your DNS. The error you will get is

450 Client host rejected: cannot find your hostname, [206.8.174.112]

Solution: Ask your internet provider to add a reverse DNS record like mail.example.com for your IP-Address.

1.1 No dial-up or DSL/Cable

Bad protected windows computers are often infected by worms or trojan horses that send mail for other people without the knowledge of the owners. They often do so by sending the spam/malware directly without using the internet access provider. It would need enormous storage and traffic if we would accept that mails. Moreover the user would have to download it, sort out and virus check. Users should use their internet providers mail server to send mail.

554 <24-182-165-208.dhcp.stls.mo.charter.com[24.182.165.208]>: Client host rejected: No dial-in accounts accepted

Solution: Ask your internet provider how to use their mail server in outgoing mail.

1.2 No free-mailer mail from third locations

So-called 'free mail' services are very popular. That is why their mail addresses are frequently faked. Other people use real or faked addresses from hotmail.com or yahoo.com. We only allow these mails if they really come from a known network that belongs to that service. If you try to send something with such a sender address from elsewhere you get:

554 <smtp6.wanadoo.fr[193.252.22.25]>: Client host rejected: You claim to be from yahoo but your mail didn't come from a yahoo server.

Why big companies like wanadoo do not realise that they are not yahoo is beyond the scope here. We told them but maybe you can convince them to get some consulting ;-)

Solution: Send your free-mail via your free-mail provider.

1.3 Sender Policy Framework

All our hosted domains use SPF. That specifies which hosts are allowed to send email from that domain. If a mail server uses SPF, it will only accept mail from legal senders for that domain. If that fails, you get a reply like:

554 <joe@turbocat.de>: Recipient address rejected: Please see http://spf.pobox.com/why.html?sender=admin%40turbocat.de&ip=85.0.202.109&receiver=celine.turbocat.de

1.4 Blacklists

Legal networks and emails are also used by spammers. That is why we use several online databases to check if the mail may be from a black sheep. Possible error messages are for example:

554 Service unavailable; Sender address [044jonggu@portsevendomain.biz] blocked using blackhole.securitysage.com; SecuritySage RHSBL4 - Please see http://www.securitysage.com/rhsbl.html

or

554 Service unavailable; Client host [83.170.241.230] blocked using sbl-xbl.spamhaus.org; http://www.spamhaus.org/query/bl?ip=83.170.241.230

Solution: Read the error message and ask the team of the appropriate anti-spam database why you are in. After you are unblocked, try again.

2. Content

2.1 Headers

We check for several Subject: contents like 'Pharmaceuticals', 'LOTTERY' and other often used things. if you get an error like:

Your email had spam-like header contents

You may have run into that filter.

Solution: Read the error message and think. After you are changed the headers, try again if you still think the receiver is interested in your mail.

2.2 Body

Some people try really hard to send their spam. But in the end, they still use their web addresses. If you have medz4cheap dot com in your message do not be surprised if you get it back without having been send to the receiver.

Solution: Read the error message and think. No, we are quite sure you do not have to send a message again.

2.3 Virus

Warning:We update our virus database every 5 minutes. 24 hours a day. But still it is possible that a messages gets into your mailbox before the virus checker knows it. If you use a common used operating system, you should consider updating your local virus checker also before fetching mail.

If our virus checker finds a virus, it will just delete the email before it ever reaches your mailbox. We will not send a error message out to the sender's address because nearly all worms and viruses fake the sender address. So why should we? Some people do so, but that is one reason for us to have a content filter.

More than you get elsewhere.

We are using email since the early days of the internet. We always try to do better than others. If some of our filters are too aggressive for you, please ask for a garbage email address. We can provide you with a address you can give to people who have a internet provider who does not understand how the internet works. We alias that garbage email to a real email of you. You do not have to change anything on your local computer. Be sure that you do not publish that garbage email address anywhere. Otherwise all the protection will be useless.