Does blocking junk mail senders help?

Does Who It's From Matter?

No. Not really. At least, not usually.

The fact is the "From:" address on spam is now an exceptionally unreliable way to identify most spam. Spammers will commonly use fake "From:" addresses, and assign them randomly. This makes it look like the message came from someone who had nothing to do with it.

It also means that the "From:" address on spam keeps changing. You may often get the exact same spam "From:" several different email addresses, even though it was all sent by the same spammer.

The result is that blocking most spam based on the "From:" address is pretty pointless. The chances that you would get spam from them again are already very low, as the address keeps changing. And, since the address keeps changing, you'll probably keep getting that same spam again, "From:" other people.

Obviously, if you're seeing a series of spam that all come from the same email address, then by all means block it if you want. However, it probably won't address the majority of what you're seeing.

You can still block all you want, I'm just saying it won't help. It'll take up a lot of time, without any real positive effect.

What Should You Do?

This is where spam blocking tools help you.

If spam lands in your junk folder, you're done. That's pretty much the best possible result. Typically there's no reasonable way to prevent the email from arriving, but at least you can have it automatically sent into the spam folder where you need not look at it unless you choose to.

If spam lands in your inbox, then use the "this is spam" button, or its equivalent if you have one, to mark the email as spam. This does several different things, including moving the spam to the spam folder. More importantly, though, it uses that email - all of that email including the message itself - to better "learn" what is and is not spam.

The more often you mark spam as spam, the better the system gets at identifying spam.

Be careful: if you mark things as spam that are not actually spam, you'll increase the possibilities that legitimate email will be falsely marked as spam.

The rule's simple: if it's truly spam (email you didn't ask for), and it's in your inbox, mark it as spam. If you did ask for it (i.e. it's a newsletter you signed up for, or a company you said "sure, send me information", then it's not spam. Unsubscribe to stop receiving it.

In the long run, your correctly identifying spam that has erroneously landed in your inbox is the best way to help the system improve its spam detection.

It'll never be perfect, we need to be clear on that, but getting mail properly filtered to your spam folder is a step.