Thanks for your response. I use an iMac. The mail program I use is 'Microsoft Office 365' (not the New Outlook) - been using it for years. Sending attachments was no problem until recently. Emails send perfectly without attachments - to various providers, but as soon as I try to send with an attachment (pdf, doc, etc), I get an error message and the email sits in my Outbox and does not send. Every so often I get this message: A secure connection cannot be established with the server smtp virginmedia.com. When I try to send an email with an attachment, it doesn't send and I get an error message at the bottom left of my screen saying Sync Error - showing the date and time 'know-smtprelay-8-imp cmsmtp ESMTP server ready' Details Email could not be sent. Attempts at sending email with attachments to @ntlworld.com,@outlook.com, @btconnect.com, @gmail.com, etc.
My Security is Norton 360/Norton Lifelock.
This only happens with the Microsoft Office 365 application - NOT with the Apple Mail or Hotmail - which I prefer not to use.
Thanks,
Joan