I had the same problem, I went into webmin in the sendmail server section,
I clicked on domain mapping.  Then I clicked on the "click here" which
took me to reconfiguring sendmail, which I did.  Must be from the patches
that came down awhile back on RHN, I never reconfigured.  Once I did this,
I could forward and reply to emails.

>> ----- Original Message -----
>> From: "Leonard, Phil" <Phil.Leonard@dsionline.com>
>
>> > I recently installed Squirrelmail and for some reason it will not send
>> mail that is created using either Compose, Reply, or Forward.  It mails
> out
>> read receipts just fine.  Any ideas?
>
>> -----
>> From: Jonathan Hutchins [mailto:hutchins@tarcanfel.org]
>
>> Could it be something to do with the temp file being created?  According
> to
>> the IMP FAQ if the process id doesn't have write permissions to the
>> configured temp file directory that's what will happen.
>
>
> ----- Original Message -----
> From: "Leonard, Phil" <Phil.Leonard@dsionline.com>
>
>> Hmm, I assume you meant Squirrelmail FAQ.  I will check that.
>
> No, I did mean the IMP FAQ - but I thought it might be relevant, since the
> process of composing and sending the message in PHP is likely to be very
> similar.
>
>
>
>