can't send mail keeps saying account is offline
MacBook Pro (13-inch, Late 2011), 10.13.6 High Sierra, no longer able to send emails, keeps saying account offline or edit SMTP, don't know how to do this or what to do. Help anybody?
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Hi,
Please make sure OS is up to date. If the operating system is not updated sometimes it can give trouble.
Secondly, check your incoming and outgoing mail server if it's your cpanel hosting email.
finally, check your port number, and incoming and outgoing ports. If you are not sure check with your hosting provider for email setup instructions.
Apple recommended as follows:
If a mailbox is offline in Mail on Mac
When an email account is offline, a lightning bolt icon 
appears next to the account’s mailboxes in the Mail sidebar and at the end of the Favourites bar.
In the Mail app 
on your Mac, do one of the following:
- Take all accounts online: Click the lightning bolt icon or choose Mailbox > Take All Accounts Online.
- Take a specific account online (if you have more than one account): Click the lightning bolt icon next to the account’s mailbox, or choose Mailbox > Online Status > Take [account] Online.
If you can’t take an account online, make sure you’re connected to the internet. If a warning icon 
appears next to the account name, click it to open Connection Doctor. Learn more about using Connection Doctor.