Delays in sending emails

I frequently get this message when I try to SEND an email, It will sometimes send the email eventually, but ! most often I close the program and restart it. It usually sends the email upon restarting. I get the following error message:

Have you opened a ticket with Suddenlink?
Have you tried this: Completely disable any VPN or Anti-Virus then try again.
Could it be that your internet connection is having problems? Try rebooting the router/modem.
If your account is IMAP then you can try removing and re-adding the account.