can someone explain the concept of "strings (or whatever) being immutable"

[Cameron Simpson]

On 02Jun2014 21:35, Deb Wyatt <codemonkey at inbox.com> wrote:
>> Please adjust your mailer to send plain text only. It is all you need
>> anyway,
>> and renders more reliably for other people.
>
>I am so sorry, I did not realize it was a problem.  Hopefully it will behave now.

Looks just great now. Many thanks.

Cheers,
Cameron Simpson <cs at zip.com.au>