Even more precisely, SPFv1 allows the owner of a domain to specify their mail sending policy, . which mail servers they use to send mail from their domain. The technology requires two sides to play together: (1) the domain owner publishes this information in an SPF record in the domain's DNS zone , and when someone else's mail server receives a message claiming to come from that domain, then (2) the receiving server can check whether the message complies with the domain's stated policy. If, ., the message comes from an unknown server, it can be considered a fake.
First impressions have a big impact on how others perceive you, so how you introduce yourself to others is extremely important. Many people call an introductory speech an elevator speech, because it should be succinct enough that you could introduce yourself and tell someone about your goals or interests in the time it takes to ride an elevator.  It may also be called an "icebreaker" speech, as it breaks the ice and lets others get to know you.  Consider your words carefully when you write a speech introducing yourself. Crafting a good self-introduction can either build or harm your credibility.