EXIM - append advert

[Alan Cox]

On Wed, 30 Jul 2008 09:53:37 +0100
Gary Stainburn <gary.stainburn at ringways.co.uk> wrote:

> Hi folks.
> 
> I've been asked to add a gif containing an advert to all outgoing emails.
> 
> Anyone got any ideas how to do this using Exim?

Its not doable. You can botch it but it will cause badness. Technically
it doesn't work out sanely, and you might want to seek legal advice on
some other points...

> I need to be able to add the gif reliably catering for plain text, HTML and 
> MIME.  

For the plain text case it isn't supported. For MIME you would need to
decide what to add it to and for HTML you will need to parse the entire
HTML document (remembering it may not be a fully valid SGML document),
analyse it somehow to deduce where to place the image in the document
validly so it will be seen and then add it. You'll then need to convert
the mail to mime multipart and add the image section as mailers won't
fetch images over the web.

As you are in the UK you also want to consider
- That adverts in mail sent outgoing to people who are not currently in
business with you with an existing relationship may contravene the
regulations on e-commerce and email.
- That if you mangle email you will break any digital signatures on
emails.
- That adding your advert to a third party work may contravene the
copyright act.
- That adding your advert to material you are forwarding which is for
another bodies trademarked product may place you in conflict with
trademark law.
- That some of your customers will probably drop all mail with images as
spam

> Also, I'd like to have a whitelist and add other filters so that it doesn't 
> get added to internal emails or existing business partners, .vacation 
> messages, Bulk emails (which we don't do, but would be nice to cater for 
> anyway) and mailing list stuff.

I think you have it backwards. I do not believe you can generally
advertise except in existing customer relationships without permission -
but you should consult your company lawyer on that matter.

> The main question is does anyone have any good examples of how to mangle 
> outgoing emails - I figure it's going to be something to do with the smtp 
> transport as that would immediately ignore all local deliveries

What you can do (and as a business may in some cases have a legal duty to
do) is to add identifiers for the business - see the recommendations on
the companies house site. Adding a new header such as Organization: is
relatively easy to do.



Alan