This probably has a very simple solution.

My outgoing emails (using Mail) seem to me to show an icon of piano keys on the right-hand side, at the top, of each one. This has been picked up from my User account.

I only chose piano keys from the icons supplied, because it was the least-silly one. I would rather have no User-icon at all.

How to get rid of it (piano keys icon showing on all my outbound emails)? I've looked at Mail preferences but cannot see anything there. I've checked User preferences but cannot see any way to disable icon.

It's not urgent, just another minor irritation.

Thanks.

Assuming you are using Mail as your email client I can think of a couple of possibilities…

1. Look at your personal entry in Addressbook (it will have an icon that looks like a bust next to the entry in Addressbook. If the icon appears there you can either put your picutre in its place, insert a corporate logo, or delete it altogether and it should disappear in your outgoing Mails.
2. …or If this is associated with your Addressbook entry, you could also create another entry for yourself without an icon or image, then select it and on the menu bar select Card > Make this my card and that is what will be used when you send emails.
3. If the problem isn't in your Addressbook check in Mail > Preferences to be sure the icon is not a Signature that is appearing before the message or that you haven't somehow selected a Stationary that has the icon embedded in it.

Thank you Joe, you were right (about Addressbook) and I have deleted that card.

Many thanks.