diff --git a/config/action.d/helpers-common.conf b/config/action.d/helpers-common.conf
index 03422a87..24e9fda9 100644
--- a/config/action.d/helpers-common.conf
+++ b/config/action.d/helpers-common.conf
@@ -4,7 +4,8 @@
 #   _grep_logs_args = 'test'
 #   (printf %%b "Log-excerpt contains 'test':\n"; %(_grep_logs)s; printf %%b "Log-excerpt contains 'test':\n") | mail ...
 #
-_grep_logs = logpath="<logpath>"; grep <grepopts> %(_grep_logs_args)s $logpath | <greplimit>
+# Wrap log lines to 900 chars to comply with SMTP line length limit (RFC 5321: max 998 chars)
+_grep_logs = logpath="<logpath>"; grep <grepopts> %(_grep_logs_args)s $logpath | fold -sw 900 | <greplimit>
 # options `-wF` used to match only whole words and fixed string (not as pattern)
 _grep_logs_args = -wF "<ip>"
 
diff --git a/config/action.d/mail-whois-common.conf b/config/action.d/mail-whois-common.conf
index ecf3a5d9..655c98a4 100644
--- a/config/action.d/mail-whois-common.conf
+++ b/config/action.d/mail-whois-common.conf
@@ -11,7 +11,8 @@ after = mail-whois-common.local
 
 [DEFAULT]
 #original character set of whois output will be sent to mail program
-_whois = whois <ip> || echo "missing whois program"
+# Wrap whois output to 900 chars to comply with SMTP line length limit (RFC 5321: max 998 chars)
+_whois = whois <ip> | fold -sw 900 || echo "missing whois program"
 
 # use heuristics to convert charset of whois output to a target
 # character set before sending it to a mail program