Hi lagos1380,
Welcome to Apple Support Communities.
It sounds like some of your emails are accidentally being filtered into the Junk folder. The instructions below will walk you the process of getting those emails out of Junk and preventing it from happening again, just follow the first set of instructions if you're using the iCloud website to check email or the second set of instructions you're checking your email with Mail on your iMac.
If you're using the iCloud website, follow these steps to unmark the message as junk.
iCloud: Manage junk mail
http://support.apple.com/kb/PH2649
Indicate that an email message isn’t junk
- Click the Junk folder in the sidebar.
- Select a message, then click the Not Junk button in the top right of the message window.
The message is moved to your Inbox. Subsequent email messages from the same sender are no longer automatically marked as junk.
If you're using Mail on your Mac, use these steps to Indicate the messages aren't junk.
Mail (Mavericks): Mark messages
http://support.apple.com/kb/PH14858
Mark messages as junk or not junk
Mail analyzes incoming messages to identify junk mail. It highlights these messages in color (by default, in brown) and adds a banner across the top of the message.
- If Mail incorrectly marked a message as junk, click Not Junk in the banner. Or click the Not Junk icon (looks like a thumbs up) in the Mail toolbar.
- If Mail failed to identify a message as junk, select the message and click the Junk icon (looks like a thumbs down) in the Mail toolbar.
When you mark messages, Mail updates its junk mail database, so it can identify junk mail more accurately.
I hope this helps.
-Jason