AT&T Mail Features

In the past few weeks I have been getting much more spam than usual. What has changed that is making the spam filter so bad?

Need to provide my email list addresses to person who will be taking over my duties in sending meeting notices to members of social organization.

Can you tell me if this email address exists?

After I click on my email, it switches to a different view that's in large print but often without the graphics. How do I get it to stop doing this?

When I compose an email and send, I get a message stating "an error occurred while sending the message". I cleaned thousands of emails out of my inbox and made sure all emails were "read". Not sure why it won't send. This happens on both the iphone app and desktop. Any assistance or advice would be