Send e-mail fails: Missing or malformed from address

Question

Within the past week or so, I've noticed a major problem with my primary AT&T / Yahoo webmail account. Sending e-mails or saving drafts fails, and I get a "Missing or Malformed From Address" error message when I try to send. I've googled the problem, but the possible solutions that I've found and tried so far have not worked:

1. Found a 2009 Yahoo Answers page addressing this issue - the solution posted there was to switch back to Yahoo Classic. I was in fact able to send e-mails in the Yahoo Classic version, but I hope there is a better way to fix this!

2. Tried clearing browser cache and deleting browser and Flash cookies - didn't help.

3. Tried to access Yahoo Help, but was sent to page saying that the version of Yahoo Mail I'm using is no longer supported, and was directed to a link to update to Yahoo's latest version. Switched to the new Yahoo, but that did NOT fix the send problem. Fortunately, AT&T provides a link to go back to the previous Yahoo Version, as the new version doesn't seem to have the news, local weather, etc.

Although I am still getting e-mails in the AT&T account, when I tried to send an e-mail to it from Hotmail, Hotmail would not send to my AT&T e-mail address. Hotmail insisted the address was misspelled or mis-formatted. Also, when I tried to use this AT&T e-mail account to sign up for this forum, the site would not recognize it as a valid address. I do have a secondary (rarely used) AT&T e-mail address, which seems to be working fine.

So, I'm totally baffled. Has anyone else run into this, or have any idea what is going on??? Thanks!

AnnieBelle · Accepted Answer

Fixed it. Was my bad, but what a process to figure it out! Tried changing my e-mail account password and accidently also changed the password for my AT&T DSL service, then lost my high speed internet connection, Spent a long time on the phone with a really helpful AT&T agent, but was unable to re-establish an internet connection, with the modem log showing entries of "authentication failed". Obtained a local dial-up connection phone number from AT&T so I could at least access the internet to (very s-l-o-w-l-y) look for solutions. Was feeling kind of naked online without the NAT router firewall, so checked my software firewall's log to make sure it was blocking probes from the internet.

And there it was. A couple months back I had added my e-mail address to my software firewall's Identity Protection Vault, and my firewall was silently blocking me from sending my address out online, and also from sending it to my modem to re-establish my credentials with AT&T DSL! LOL!

Solved.