Mail gone haywire?

For some years I have received emails from a discussion forum without problems, with incoming emails automatically stored in a particular mailbox folder.

But the last 2 days the emails received from that forum have included loads of surplus characters such as:

&gt;&gt;&gt;&gt;&nbsp;<br>

&gt;&gt;&gt;&gt; Regards,&nbsp;<br>

&gt;&gt;&gt;&gt;&nbsp;<br>

&gt;&gt;&gt;&gt; Eddy&nbsp;<br>

The problems only seem to happen on Apple Mail 1.2.5 (v553) on G4 iMac on OS 10.2.8 but the forum emails seem OK on both

Apple Mail 1.3.3 (v612/624) on G4 iBook on OS 10.3.9

and on YAHOO Mail.

So is there anything I can do to iMac to make it behave the way it used to do?

I have considered using "Rebuild Mailbox" but wonder if that would do more harm than good.

Any ideas?

I have now set up a new mailbox folder with a different name to receive the emails from the forum.

It seems to work OK so panic over ( till the next time ).

As an aside, using 'Rebuild Mailbox' did not improve matters.