[ Help needed ] Creating sieve script where recipient & sender email address is ident

[JeremyNicoll]

Originally Posted by xyzzy

I'm testing for plus addressing ....

Yes, I understood the intent.

Originally Posted by xyzzy

In general the first backslash is "consumed" by the Sieve string scanner which passes what follows to the command.

Ahhh... Now I come to think of it I've seen Sieve use backslash to escape a double quote within a string (which is of course always enclosed in double quotes).


Looking back at the first RFC for Sieve, RFC3028, this is described. And interestingly it says that the only required Sieve parser escape sequences are backslash backslash, and backslash doublequote which I think means (unless a later RFC changed it) that

Originally Posted by xyzzy

... header :regex "X-Spam-score" "^5\.[6-9]$" ...

is actually correct. That is, the Sieve parser won't swallow that backslash because it's not followed by either another backslash or a double quote!

Or maybe not. The RFC also says: 'an undefined escape sequence (such as "\a" in a context where "a" has no special meaning) is interpreted as if there were no backslash (in this case, "\a" is just "a").' .... Which seems to me to be weird, because it seems to say that the escape character is elided in those situations, which means it IS being treated as an escape character and not a literal.

[xyzzy]

Originally Posted by JeremyNicoll

Originally Posted by xyzzy
...header :regex "X-Spam-score" "^5\.[6-9]$")...

is actually correct. That is, the Sieve parser won't swallow that backslash because it's not followed by either another backslash or a double quote!

Or maybe not. The RFC also says: 'an undefined escape sequence (such as "\a" in a context where "a" has no special meaning) is interpreted as if there were no backslash (in this case, "\a" is just "a").' .... Which seems to me to be weird, because it seems to say that the escape character is elided in those situations, which means it IS being treated as an escape character and not a literal.

Look at it this way; for Sieve (and many other languages, e.g., C, C++, etc.) the backslash is always considered as the "escape character" indicating the character that follows it may have special meaning. If it doesn't the character that follows is used as-is.

So if you are a "purist" then that "^5\.[6-9]$" is incorrect but it's just not worth the ticket pestering FM about it since that '.' in the context of this regular expression for the spam score will match any character there but it's always going to be a '.' anyhow since FM always formats the spam score correctly.

[SideshowBob]

Originally Posted by xyzzy

So if you are a "purist" then that "^5\.[6-9]$" is incorrect but it's just not worth the ticket pestering FM about it

It doesn't matter in this case, but people might use it as an example in their own code.