I am getting several hundred emails daily of some sort of "delivery failure" -- of messages I didn't send. Someone else is sending them out using my email address. Is there anything I can do about this?
E-mails can be spoofed. E-mail accounts can also be hacked.
Any decent e-mail anti-spam system should be checking the sending records of the machine sending out the e-mail and also validating the sender against the address (and checking for changed "Sender" addresses). Those rejection/failure messages may be due to this or due to invalid e-mail addresses.
I'd start off by changing your e-mail password just to be sure. If you use a program on your computer for e-mail such as Outlook or Windows Live Mail, make sure you run a routine malware scan to ensure nothing on the machine could be causing that too. Malwarebytes and SUPERAntiSpyware are awesome programs to run.
If someone from another server is spoofing your e-mail, just leave things be. They eventually stop. You can also set up filters if the sending server is the same to have the e-mail account instantly delete any delivery failure messages generated by a certain spoofed sender.
The same thing is happening to me, sort of. I also am getting literally hundreds of these assorted firstname.lastname@example.org, email@example.com and other unique individual ones. The difference is they all show an email address i'm not familiar with, firstname.lastname@example.org or something similar. Now, is that my master email or something because I don't have any sub accounts. Also, none of these messages that have "failed" appear in my sent messages. Where are they coming from and how do I stop them?
Unfortunately Verizon has an irritatingly poor email system whereby it cannot identify Spoofed emails. Therefore there is nothing you can do short of changing email addresses besides hoping that the offender stops eventually.
Feel fortunate if all you get are a lot of undeliverable email notices. Many Verizon users, including myself, have repeatedly had our accounts blocked and forced to change passwords ... all because Verizon errantly assumes the account was indeed responsible for all the spam.
Nothing can totally identify spoof'd messages, since email is allowed to come from other locatation other than the users home domain. Also users can authorized some sites to send email on their behalf, e.g. announcing a ecard or gift from you. The various email sites can check for some consistency and for known spoofing locations.
Verizon's answer to email address spoofing is bull**bleep** just like their effort to stop telemarketing and spoof'd callerid names. They just don't want to be bothered. Take the plunge and use Gmail and you won't have to deal with lame techsupport and bull**bleep** resolutions.
The third party filter was being maintained for years from your forwarded emails. Note THEY DO NOT USUALLY filter simply by email senders name. It seems to be falling apart in reason years as spammers get more sophisticated. Doesn't help that they now they are being replaced as Verizon had announced its intent to move everyone to the AOL (a Verizon company) interface which has its own Spam filter.
Note real spoofing of email, as opposed to spam, that isn't encrypted or signed is almost impossible to stop under the current email protocols. Only the original ISP/email provider can tell if the account is really from the sender. Compounding this is that some services even send email on your behalf that is sent as if it is form you.