[Dovecot] Set vszlimits for some services to prevent oom situations, fixes #1203

data/conf/dovecot/dovecot.conf

@@ -209,19 +209,21 @@ service managesieve-login {
   }
   service_count = 1
   process_min_avail = 2
-  vsz_limit = 64M
+  vsz_limit = 256 M
 }
 service imap-login {
   service_count = 1
-  vsz_limit = 64M
+  vsz_limit = 256 M
   user = dovenull
 }
 service pop3-login {
   service_count = 1
+  vsz_limit = 256 M
 }
 service imap {
   executable = imap imap-postlogin
   user = dovenull
+  vsz_limit = 256 M
 }
 service managesieve {
   process_limit = 256