fix(smtp): skip the reverse DNS lookup of connecting clients (#104)

smtp-server reverse resolves every connecting client before it sends the
220 greeting, unless disableReverseLookup is set. MailDev never reads the
resolved hostname, and without a network the lookup does not answer, so
each connection waited for smtp-server to give up on it.

.changeset/fix-smtp-reverse-lookup.md

@@ -0,0 +1,8 @@
+---
+'@maildev/smtp': patch
+'maildev': patch
+---
+
+Skip the reverse DNS lookup of connecting SMTP clients (#104). The resolved
+hostname was never used, and without a network the lookup held back the
+greeting on every connection until it timed out.