Create u_e-clamav-whitelist.en.md

docs/manual-guides/ClamAV/u_e-clamav-whitelist.en.md

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+## Whitelist specific ClamAV signatures
+
+You may find that legitimate (clean) mail is being blocked by ClamAV (Rspamd will flag the mail with `VIRUS_FOUND`). For instance, interactive PDF form attachments are blocked by default because the embedded Javascript code may be used for nefarious purposes. Confirm by looking at the clamd logs, e.g.:
+
+```bash
+docker-compose logs clamd-mailcow | grep "FOUND"
+```
+
+This line confirms that such was identified:
+
+```text
+clamd-mailcow_1      | Sat Sep 28 07:43:24 2019 -> instream(local): PUA.Pdf.Trojan.EmbeddedJavaScript-1(e887d2ac324ce90750768b86b63d0749:363325) FOUND
+```
+
+To whitelist this particular signature (and enable sending this type of file attached), add it to the ClamAV signature whitelist file:
+
+```bash
+echo 'PUA.Pdf.Trojan.EmbeddedJavaScript-1' >> data/conf/clamav/whitelist.ign2
+```
+
+Then restart the clamd-mailcow service container in the mailcow UI or using docker-compose:
+
+```bash
+docker-compose restart clamd-mailcow
+```
+
+Cleanup cached ClamAV results in Redis:
+
+```
+# docker-compose exec redis-mailcow  /bin/sh
+/data # redis-cli KEYS rs_cl* | xargs redis-cli DEL
+/data # exit
+```