It shows something like this:
spamdyke[5784]: ERROR(tls_init_inner()@tls.c:236): unable to load SSL/TLS certificate from file: /var/qmail/control/servercert.pem : The operation failed due to an I/O error, Unexpected EOF found, error:0200100D:lib(2):func(1):reason(13), error:20074002:lib(32):func(116):reason(2), error:140DC002:lib(20):func(220):reason(2)
Receving mail works fine. Same cert works great for Kloxo and web server.