[exim] MTAs and self signed certificates

Hi All,

I got the following from a another mailing list, and I so I thought I would ask this here.

I'd like to know if I can expect problems with using TLS and a self signed
certificate.

Does anyone know if there are such MTAs out in the
wild, or is it plain bad form to use non-Veryslime signed certificates on a
public MTA?

Kind Regards
Brent Clark