On 2012-05-24 17:07 , Benoit Panizzon wrote:

Heya

Another one on about the same topic.

Business Customer with own Mailserver. They ofter want to know, which of our mailservers they can use as smarthost. We usualy tell them, that they operate an own fully connected mailserver which does not need any smarthost to deliver email to the world.

Some do not agree. The reasons the tell us are:

• It Tech XY has told them that sending via a smarthost is much more reliable.

Then you setup a box which acts as that and let them pay for it too ;) After explaining them why it does not matter of course...

Smarthosts can be very useful if their mailsystem is located on a unstable DSL link for instance which might have a random IP that belongs to others at times.

• Their previous ISP asked them to use it's smarthost.

Explain that the previous ISP only wanted their cash and data.

• Our Server has better 'reputation' than theirs and thus emails are less

likely to be considered spam by some spamfilters.

That can be a valid argument, but typically if you share an outgoing system you also might have another customer that is sending spam which gets that outgoing system blocked, thus if it is really valid argument, not sure.

• Some seem to see DNS issues which I never could understand (they have

correct PTR and MX settings for their mailservers).

Some admins are ***** and do not check/monitor their settings and configuration, bad things happen that way ;)

The problems I see with smarthosting are:

• If an email to a recipient does not make it there, we get the blame even on

trivias like 'user unknown'.

• We have to punch holes in the anti-spam thorttling measures to allow them to

send more emails / time than the usual private customer does.

• They can generate huge load peaks if they operate newsletters and similar.

Yep, but they are paying thus these should not be an issue.

• They often do relay bounce emails for strange reasons, or cause mail loops

which we do not want to be routed via our infrastructure.

That is a configuration issue that can be avoided.

• The risk that our infrastructure get's blacklisted because of trojan

activities on a customers infrastructure increases.

You should keep your own infra separate from your customer infra. You could even go as far as giving every user their own Virtual Machine and IP with their own configured mailserver.

If you use something ala LXC you could host thousands of these backups on the same gear very cheaply. Of course Xen/KVM/vmware allows you to accomplish the same. The advantage of course of VMs is the ability to move them around to other hardware where needed.

So how do other ISP handle such requests? Do customer with an own fully connected mailserver have any reason to use their ISP's email infrastructure as smarthost?

Them hosting it on an unstable link with changing IPs might be the only thing...

Greets, Jeroen