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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.:

docker compose logs clamd-mailcow | grep "FOUND"

This line confirms that such was identified:

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:

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:

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

Last update: 2022-08-31 14:45:46