The threee tags `<name>`, `</name>` and `<command>` were frequently used
with a leading space that this removes. The reason this habbit is so
widespread in testcases is probably that they have been copy and pasted.
Hence, fixing them all now might curb this practice from now on.
Closes#12028
... and add "MAILINDEX".
As described in #2789, this is a suggested solution. Changing UID=xx to
actually get mail with UID xx and add "MAILINDEX" to get a mail with a
special index in the mail box (old behavior). So MAILINDEX=1 gives the
first non deleted mail in the mail box.
Fixes#2789Closes#2815
