firstname.lastname@example.org is a spamtrap; the address appears ONLY on this webpage, so when mail to that address appears, the sender is known to be a spammer.
Bouncing mails is a bad idea and is becoming widely frowned upon these days, because the bounce often goes to the wrong place. Hence MailWasher's facility to bounce mails deliberately is a particularly bad concept.
Consider the categories of mail you're likely to bounce:
Here's another thought: have you ever received a spam advertising a
CD with millions of addresses on it,
i.e. a DIY become-a-spammer kit? Well, if you receive lots of spam, it's likely that your email address is one of the
millions. That's on a CD-ROM distributed to as many
as the spammer can sell it to. What effect would receiving a bounce have on
the spammer selling that CD? Exactly. None. The spammer can't recall the CD and
remove your address from it, and in practice the spammer won't even remove your
address from subsequent versions as that would (a) be too much trouble, and (b)
reduce the number of addresses on the CD, making it less attractive to potential
buyers. These CDs are already jam-packed with munged addresses,
Message-Ids that look like email addresses and plenty of other undeliverable addresses,
so they're not going to worry about another one.
So you see there's not a lot of benefit to using the "bounce" option, other than the satisfying feeling you might have got from thinking you've got one over a spammer, but there are significant drawbacks, and they mostly involve sending mail to other innocent parties.
Moreover, it's possible that the very act of using the "bounce" facility may violate your own ISP's terms of service, because in some cases the bounce message generated by MailWasher may use a sender address belonging to your ISP. If the "bounce" itself generates a bounce (quite likely, since the original sender's address may not exist, as mentioned earlier), then your ISP will get the bounce of your "bounce". Rest assured they won't be terribly pleased to see this, as you have been forging their addresses and dumping unwanted mail into their mailbox.
By all means, use MailWasher to delete mail from your mailbox, but please don't use its bounce facility - you'll only annoy other regular mail users, not the spammers.
Don't just take my word for all this - check out this link too. There are instructions there for how to turn off the bouncing facility in a variety of products, not just MailWasher.
email@example.com is a spamtrap; the address appears ONLY on this webpage, so when mail to that address appears, the sender is known to be a spammer.