Q: sending email using smtp under Yosemite

Have a problem sending email via smtp - Macbook Pro 10.10.3 Yosemite - need to reboot constantly to send email unless using iCloud. Is this a general issue? if so do we await an amendment to Yosemite.? Or is there another solution - have deleted and re-input email accounts already. Have changed UserAllows.Insecure.Authentication from True to False to no effect. Thanks.