my mac can't send from my gmail accounts

Help us help you:

1) What iMac model? There are literally hundreds of iMac variants made since that model name was first used in 1998

2) What Mac OS version?

3) What Browser are you using?

4) Are you running any anti-virus or "cleaning/optimizing/tune-up" software?

Whan a friend has simialr issues, he had to contact Google support to get it sorted.

PS: Although hard to tell from the title,this forum is for Mac hardware made before 1998.

... it can't connect to server smpt.gmail.com.

It should be smtp.gmail.com.

Check your Mail account settings. Mail menu > Preferences > Accounts > select the account > Account Information > Outgoing Mail Server.