[Dovecot] Check file size of mail crypt key pair, fixes #1859

[Compose] New Dovecot image

data/Dockerfiles/dovecot/docker-entrypoint.sh

@@ -117,7 +117,7 @@ echo ${RAND_USER}@mailcow.local:$(doveadm pw -s SHA1 -p ${RAND_PASS}) > /usr/loc
 echo ${RAND_USER}@mailcow.local:${RAND_PASS} > /etc/sogo/sieve.creds
 
 # 401 is user dovecot
-if [[ ! -f /mail_crypt/ecprivkey.pem || ! -f /mail_crypt/ecpubkey.pem ]]; then
+if [[ ! -s /mail_crypt/ecprivkey.pem || ! -s /mail_crypt/ecpubkey.pem ]]; then
 	openssl ecparam -name prime256v1 -genkey | openssl pkey -out /mail_crypt/ecprivkey.pem
 	openssl pkey -in /mail_crypt/ecprivkey.pem -pubout -out /mail_crypt/ecpubkey.pem
 	chown 401 /mail_crypt/ecprivkey.pem /mail_crypt/ecpubkey.pem

docker-compose.yml

@@ -160,7 +160,7 @@ services:
             - sogo
 
     dovecot-mailcow:
-      image: mailcow/dovecot:1.38
+      image: mailcow/dovecot:1.39
       build: ./data/Dockerfiles/dovecot
       cap_add:
         - NET_BIND_SERVICE