Outgoing SMTP / ‘smarthost’ service
Please note that this service is primarily for ADSL customers who do not want
to set up an outgoing SMTP server on their home or office machines.
Configuring your Virtual Machine to properly send email can be difficult.
Accidental misconfiguration can result in your machine being an unwitting relay
for spam, or junk email (a sin for which most internet providers will block
your mail server for, including us), or to silently swallow outgoing email for
days instead of sending it to its destination.
A ‘smarthost’ is a mail server set up by an internet provider which accepts
mail for customers and delivers it on their behalf. We provide such a server
and we will relay messages that fulfill the following criteria:
- The envelope MAIL FROM: address must be routeable (i.e. exist and have a
valid MX record)
- The envelope RCPT TO: address must also be routeable.
- To connect to the relay your host IP address must be in the Bytemark IP range.
- The message must be 20MB or smaller.
- Your machine is not sending more than 160 messages every 6 hours.
More details about the configuration of the server can be found on the
You can configure your mail software to use ours by telling it to use:
Disadvantages of using this service
The biggest disadvantage of this service is that your email is being delivered
by the same machines that handle other people’s mail. Since this is an open
service for our customers, these servers are vulnerable to being blacklisted if
one customer decides to use them to relay spam. Once listed, it can be
difficult to get them removed, especially when certain lists do not publish
As a result, this service is really a last resort for people not wanting to
relay email themselves. All Dedicated Hosts and Virtual Machines are configured
to relay email directly, rather than via this service.
We’d encourage people with VM or Dedicated Hosts to move away from using it if possible. If you need help doing this, please drop a line into support .