[blueskin_]

>Is this your opinion, or fact?

Well, it depends on the feature set you need, but to a level that most people might consider fact.

From memory, no support for TLS connections, SMTP AUTH, or SPF/DKIM on mail. That, plus it has very limited support in general and needs an arcane collection of patches to remain workable.

Other mail servers can work around its restrictions, yes, but that doesn't make it fit for purpose.