I expect that you guys and girls have the same problem.
Getting unsolicited emails and phone calls. I mark the email as spam. but see no reduction in those emails.
When I get phone calls, I tell them that I did not invite them to call me and to put me on their do not call list.
Is that a waste of time as well?
I have had a great week. 
I think on most systems when you mark them a spam they then go into the spam folder if the address is exactly the same. Then you can ignore that folder and after a specified amount of time they get removed by the mail client. They tend not to reduce spam because spammers use fake addresses that change everyday. That makes it very hard to block emails.
On cell phones there are blockers you can install to block certain numbers but again they spoof the numbers and they change all the time. We still have a house phone and I purchased a phone that gives people a three digit code they must input or it kicks them out (people in the phones phone book are automatically connected). That eliminates computer dialed calls, it has to be a human to ring through. It also allows me to block specific numbers, which I do if it is to persistent a marketer or a toll free number, along with certain numbers I know are political calls around election time.
In about two year of having bought that phone it has blocked over 1000 robocalls and at least 200 perisitent callers. I love that phone.
Spam is sadly a fact of life. I've been using the excellent SpamSieve (C-Command Software) for close to 30 years and it's reduced the clutter in my inbox significantly.
As for requesting it to stop, you might as well spit into the wind. On rare occasions, the sender will honor your request (I've found this true mostly on political pandering messages). Most of the time, sending an unsubscribe message will simply confirm your email as being correct and active, and result in even more spam (gathering and selling email addresses is big business. Just ask Google).
Using a robust filtering solution such as SpamSieve (Mac only) has been the best answer for me. I can't stop others from sending spam, but that doesn't mean I have to see it.
Having a landline is good. Since they have their own power supply,
it always works.
It's not really a landline it is VoIP (Voice over Internet Protocol). We use Magic Jack for our home phone. If there is a power outage or ISP outage it goes out, both my wife and myself have cell phones for emergencies.
A lot of spam has to do with your activity on the Internet. If you use Yahoo or Google to post, your post has your screen name, which is also your email address in it. Another thing is if you have friends that forward emails with joke, memes and even news stories. You sometimes see twenty or thirty names with email addresses on the To: line. You have no idea who those emails are being forwarded too. I had a brother-in-law who loved to do that and my spam increased tremendously when he was doing that. I always wipe out all addresses except mine when I forward something. Suggesting that to friends and families can help. Some sites and even government agencies sell your email address, you can often opt out of stuff. I finally closed my Yahoo account and use two security emails and have never gotten even one spam on either of those. I have Gmail because I have an android phone, and if I have to sign up for something that spams like grocery store discount cards that use your email and then just ignore it, eventually Gmail deletes all the spam.
I do not send group texts. And I often do not have my phone with me. I do not feel the need "to always be connected to the world."
A landline came in handy when a hurricane knocked out cell towers while I was taking care of my mom when she had dementia.
That sounds a lot like a "whitelist callblocker". You used to be able to buy these here (east of The Pond) but they disappeared before I was able to buy one.
What is "east of the Pond"?
Europe. Although the Brits (and the Yanks) are the ones who mostly use the term "pond."
"The Pond" is slang for the Atlantic (= understatement humour)
Yankee : It can also be a derogatory term for Americans used by those outside the US, sometimes perceived as offensive, [according to Collins Dictionary]
Do you think "Americans" might be a better definition?
Personally, as an American, I take no offense at slang terms used to describe us. In fact, Americans may be the champs when it comes to creating our own (sometimes derogatory) nicknames: Cracker, Hillbilly, Redneck, etc. During the world wars, soldiers had nicknames for allies and foe alike: Tommie (British), Jerry (German), Nip/Jap (Nipponese/Japanese), Ivan (Russian) and the aforementioned Yank (some would refer to "Johnny Yank"). George M. Cohan even wrote "Yankee Doodle Dandy," which was a patriotic song written for Broadway.
A song with what was (and still may be) the longest-ever name was "I'm a Cranky Old Yank in a Clanky Old Tank on the Streets of Yokohama with My Honolulu Mama Doin' Those Beat-o, Beat-o Flat-On-My-Seat-o, Hirohito Blues" (written by Hoagy Carmichael).
So, even if "Yank" is considered a derogatory term by some, Americans are self-deprecating enough to not take offense.
Wars almost always create de-humanizing slang names. It makes it easier for troops to kill enemy soldiers as most people are adverse to killing humans. Dehumanizing others helps them to do that. Most of those terms are only used by people thinking they are better than others, self appointed elites. I live in the Midwest and have never in my 69 years heard anyone here call the Atlantic Ocean 'the pond'. If it was that common Andy would have known it too.
You used to be able to buy these here (east of The Pond) That would indicate a European.
I did not take the term very seriously. I am a very happy guy.