Alerts as .dat attachments

Perhaps someone can help me shed some light on this. I'm receiving some
red alerts as .dat attachments. Is this normal behavior?

red Mon Feb 13 20:33:11 2006: /Ping.tst Set-Cookie: JSESSI

&red http://10.228.3.4/Ping.tst - /Ping.tst Set-Cookie: JSESSI

HTTP/1.1 404 /Ping.tst Set-Cookie:
JSESSIONID=100BAAD89BF9FB00920DA09504FEB4B1; Path=/ Content-Type:
text/html Date: Tue, 14 Feb 2006 04:34:21 GMT Server: Apache-Coyote/1.1
Connection: close 
Seconds:     0.00

See (hobbit URL here)

Hobbit-alerts.cfg:

$NSHOSTS=%(sc-isus-ns-1|sc-isus-ns-2|sc-isus-ns-3|sc-isus-ns-4|sc-isus-p
w-1).subdomain.domain.com

HOST=$NSHOSTS SERVICE=http
        MAIL isus-sms REPEAT=2h RECOVERED COLOR=red FORMAT=sms

HOST=*
        MAIL isus-mail REPEAT=12h RECOVERED COLOR=red
EXHOST=sc-isds-1.subdomain.domain.com

UNMATCHED
        MAIL user-6d630c347185@xymon.invalid COLOR=red REPEAT=12h RECOVERED

Is this a default behavior I didn't know about? It doesn't seem to be
consistent. I've looked through the online page about configuring
alerts. Perhaps I've missed something in my alerts.cfg. Thanks!