My email sent with Mac.com email is going to recipient's junk mail [started this year]

Do the eMails get marked as spam if sent through WebMail in a browser?

We need to see what all is running, a report from this will not display any personal info...

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Pastebin is a good place to paste the whole report if you capture the URL while there…

Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

It may be your ISP or IP Range is being used by spammers.

To see if it's your provider, What's my ip...

https://www.whatismyipaddress.com/

Start with these three, check SpamCop or SpamHaus to see if your IP is there...

https://spamcop.net/bl.shtml

https://www.spamhaus.org/lookup.lasso

https://www.spamhaus.org/zen/

Sometimes an ISP will bloc a whole other ISP too, if it's the source of too much SPAM.

Mail does this. All platforms. Always has. It’s getting worse too, with changes some major vendors are implementing. Changes likely to cause users to migrate to specific and larger mail services, too. Recipients can mark the messages as not spam. There is not, however, any control or button or setting that will cause your mail to be considered not spam. There are, however, ways to create mail messages which will increase the likelihood that the mail messages will be considered spam. And all mail providers are having issues with users sending spam from their services, too. Yes, we’re probably eventually all going to have to whitelist, too. Or migrate to other communications mechanisms.

What to do? Recipients should whitelist. Avoid sending out “spammy” mail messages. Expect some messages to get filtered. Consider using alternative and preferably more reliable mechanisms to communicate, too.

Complain to Google, as it’s their mail server and their spam filtering and their data acquisition efforts doing this, not that I suspect they’ll seemingly be any less evil in what appears their efforts to encourage everybody to migrate over to Google-provided mail and Google services.

Victoria Herring wrote:

It's not going to just Gmail = it's going to almost everyone with whom I have communicated by email over the years.

What’s remarkable is that mail works as well as it does, with the competitive interests seeking to shift it to their advantage, whether that’s spammers spamming spam, or commercial interests running anti-spam services, or advertisers running massive platforms seeking to collect and track data.

Spam-filtering and spam defenses will mischaracterize and will make mistakes, and spammers will trigger new issues with mail from others sharing the same servers. (And low-traffic or unknown mail servers will usually be assumed to be malware spam engines.)

Put differently, mail is mail, it mostly works, and it does not and will not be entirely reliable.

Use an alternative for communications. Or use mail in a way that does not scan as spam. Or ask your recipients to train your mail traffic as valid. Or a combination. And expect some mail to get canned, particularly if it is even remotely spammy.

Not likely the cause if the problem, but still needs to be cleaned up...

Delete this file & restart...

~/Library/LaunchAgents/com.adobe.AAM.Updater-1.0.plist

~ tilde indicates your home folder

Apple hid the Users' Library folders...

Method 1:

1 From the Finder, select the Go menu at top of the screen, and choose Go to Folder.

2 In the window that opens, enter ~/Library, and click Go.

Seems lots of crashes due to file usage, spotlight, photo analysis, & syncing.

You can use Drive DX to possibly get a better view of Drive health…

https://binaryfruit.com/drivedx

Thanks to Jack-19…

It may be wise to run SMART Utility to check the drives' health. 

Sure sounds like your IP or ISP is being blocked.

Thanks