Forum or newsgroup messages :
An email service or email the individual members to send messages to all group members to read ("many to many"). In contrast, a newsletter is a post from one to many.
A legitimate message, which has a legitimate content and adhering to technical standards, but is mistakenly rejected or filtered as spam, either by an ISP or application of a recipient anti-spam. The tighter anti-spam application, the greater the rate of false positives.
Many providers of e-mail service like Hotmail, work with the Bonded Sender program.
Everything that appears in the email address or email of the recipient as the visible name of the source. Chosen by the sender. It can be a proper name, a brand, an e-mail address, a blank space, or the number of hash. The real return address contained in the email header can be different, ie the email address of response may be different. The "de" is easy to fake.
Full Email service providers:
An email provider that also provides consulting services in strategic and creative aspects of the campaign and send messages.