unable to send emails

I will make some assumptions. First is that you are using the Mail app. The second is that you have done nothing or changed anything which may have caused the problem. If this is incorrect, please advise. You say that the "In account server settings it says my outgoing mail server account is offline". Is this information you are receiving from the email providers web site which you have accessed via a browser? If so, it is their problem to solve and you should contact them. If not, then it means that the Mail app is unable to respond to the servers request for your ID and password for some reason, and then the server's access times out. If this is happening you need to carefully check the ID and passwords you have in Mail's settings and correct them. Sometimes it is easier to delete the account in Mail and set up a new one.

Yes email providers have different host names for incoming and outgoing messages. And Mail must accurately match them in the Mail settings as well.