Gmail isn't for everyone. The Web-based email platform doesn't work like other email platforms. Messages show up as groups that turn into conversations. This conversation-style of organization can be a bit overwhelming, and messages stack up pretty quickly. But once you get the hang of the interface and learn how the search function works, finding and organizing your messages becomes second nature.
Unlike other email programs or Web-based interfaces, Gmail doesn't stack your messages in chronological order. If you receive five emails from one sender with the same subject line, Gmail will clump them together. The same goes for your other messages. When a message in a conversation is new, that entire conversation moves to the top of the order, and messages appear in your inbox by sender first. That's why you'll see the names of the people involved in the conversation one after the other. This organization method comes into play when trying to find forwarded messages, because email programs add "Fwd" to the front of the subject line, changing how Gmail reads the message.
When you forward a message in Gmail, its subject line changes from, for example, "Tips on Puppy Care" to "FWD: Tips on Puppy Care." Open any conversation with several messages in Gmail, and you'll see all of the subsequent messages listed in order. The trick is, when you forward a message its new title (new subject line) excludes it from Gmail's organization. Immediately after sending a forward, you'll see a yellow box stating, "Your message has been sent. View message." The message is in a new conversation, but it won't appear in your inbox until someone replies to it.
Gmail grows infinitely, so unless you have emails with large attachments, you'll never have to delete your message. This means that your inbox fills up quickly and you have to search to find specific messages -- which prompted one of Gmail's early slogans: "Search, don't delete." To find a forward, type the subject line of the message into the Gmail search box.
Gmail has a lot of built-in spam prevention features, and while not typically configured to block forwarded messages the spam filter adapts to behavior. If you've repeatedly clicked "Mark as spam" for forwarded messages, the filter might have changed to block all forwarded messages. Click the gear icon in Gmail and choose "Mail Settings" and then choose "Filters." Add a filter allowing all messages with "FWD" in the subject line, and all forwards from other senders will go directly to your inbox.