What is preferable, "no-reply@" or "noreply@"? [closed]

Having a service that sends out notifications to users, I'm currently thinking about changing the sender email address from "info@" to something more meaningful.

Since a reply never makes sense, I'm thinking about using one of those "no reply" email addresses.

After doing some checks through my email inbox from the last 10 years and some Google search, I'm not sure which one is "better" (in terms of more likely to not be filtered out by Spam checkers) to use:

• "noreply@mydomain.com" -or-
• "no-reply@mydomain.com"?

Also, I'm not sure whether the difference matters at all.

So my question is:

Which kind of "no reply" e-mail address to use and why?

Either is completely acceptable so long as you configure the basics (DNS, SPF, DKIM is a good idea... etc). Make sure your software properly responds to 4xx and 5xx errors. Spam filtering rarely considers the e-mail address, except upon repeat messages (keeping track of "reputation" so to say).

Side note: in geekier communities I've seen bit-bucket used as well; though the general public is not expected to "get" that reference. All my domains "accept" e-mail at this address (along with all the RFC 821 required addresses).