Have a .NET program that uses the System.Net.Main namespace to send an email via SMTP.
Its on a customers site so from there it will go via a (series of?) SMTP relay servers before it reaches its destination.
At the moment I have no information about this smtp replay / email infrastructure (and getting that information is going to be hard).
Somewhere along the line an exclamation mark is being inserted into long URL's in the the email around 100 chars in from the start of a line.
EDIT- Actually have found its about 1000 chars in
This is not happening on a test system or hundreds of other sites.
I feel sure this has to be something to do with escape codes to break long lines up.
Anyone got any ideas?