The underscore seems to be a safe bet and the deliminator could be something as simple as a double underscore "__" or even "ZZZ" - anything that wouldn't be "commonly" part of an email address.  Ideally, having a setting where you could set your own deliminator would be best.

My favorite feature of Mercury is the ability to "Allow the use of "+" forms in addresses to carry user-specified data".  However, there are many problems with using the "+" sign on many web-based forms and many sites will not allow the use of a "+" sign in an email address.  Is there any possibility that future versions of Mercury would allow the customization of the character that is used as the deliminator?  Is there any undocumented way to change it in current versions without waiting for a future update?

[quote user="Martin A."]My favorite feature of Mercury is the ability to "Allow the use of "+" forms in addresses to carry user-specified data".  However, there are many problems with using the "+" sign on many web-based forms and many sites will not allow the use of a "+" sign in an email address.[/quote]

Agreed - that's what I've found as well.  But these sites usually also block most other non-alphanumeric characters.

[quote]Is there any possibility that future versions of Mercury would allow the customization of the character that is used as the deliminator?[/quote]

I've not seen any discussion on this.  Although the standard (rfc5233) doesn't limit the character used as a separator, there's quite a scope for problems if an unusual separator or mix of characters is used.

[quote]Is there any undocumented way to change it in current versions without waiting for a future update?[/quote]

Nothing that I know of.

Most things are possible in Mercury but some are more complicated than others. In this case it would probably be possible to write a MercuryS event daemon to accept some other separator as well and presumably just replace it with a plus sign to keep internal handling intact.

/Rolf 

Writing daemons for Mercury is something that I've never done.  I'm sure that if that's what I have to do, I can figure it out.  But before I go to all the trouble of acquiring a C++ IDE and putting in the time to learn the language and the Mercury API, I would want to know whether the daemon process would run before the message would process through the Core - because it would be rejected at the core level if it wasn't recognized as a local address/user.

A MercuryS event daemon intercepts the SMTP transaction with the client, and can modify both SMTP envelope headers and the message before it's delivered to core for further handling. Have a look at the official daemon developer kit for more information:

http://community.pmail.com/files/folders/mercur/entry10073.aspx

Messages received by other means than SMTP would not be seen by the daemon, though.

/Rolf