How to refuse delivery of "No Sender" messages?

[Guest]

I receive periodic messages with "No Sender" or blank "From" block as well as
"No Subject" in the "Subject" block. This appears to be an attempt to verify
one of my email addresses possibly for the purposes of generating spam. The
"Rules" area doesn't seem to have an option to apply a delete rule to a
message that is delivered with "No Sender".

Any suggestions?

Thanks,
Martin

 

[Vanguardx]

I receive periodic messages with "No Sender" or blank "From" block as
well as "No Subject" in the "Subject" block. This appears to be an
attempt to verify one of my email addresses possibly for the purposes
of generating spam. The "Rules" area doesn't seem to have an option
to apply a delete rule to a message that is delivered with "No
Sender".

Any suggestions?

Thanks,
Martin

Well, what does a valid sender have? An e-mail address. What does a
validly syntaxed e-mail address have? The at-sign ("@"). So define a
rule to delete all e-mails except those that have "@" in the From
header.

What is a blank Subject? A header with no words in it. What do most
words have? Vowels. Is it likely that you will receive a message with
a non-blank Subject that has no vowels (like "Psst, Mr. 'n Mrs. TV")?
No, but it's possible. So define a rule to delete all e-mails except
those where the Subject contains "a", "e", "i", "o", "u", and "y" (or
include all characters "a" to "z", inclusive, if, for example, you
receive lots of e-mail from senders writing in Welsh or Hebrew). You
could add numbers to the list but how often have you received a good
e-mail that had only a number as its Subject?

Think in reverse. Delete it *unless* ...