Here is probably a stupid question yet I have not found a definitive answer to it. My mailbox.log file is full of entries like below.

At first glance it looks to me like some kind of armageddon/end of all humanity type error but on more careful consideration I am 'assuming' (I hope correctly) that it simply is not supposed to index certain headers/long text strings that would not be useful to have indexed and that the warning I am seeing is the intended and proper behavior of not indexing those headers.

Is that in fact the case? Since it ends with "Re-index completed items=4170,failed=0", all is good despite the warnings?

Just trying to understand it all.

Code:
2012-10-05 10:12:04,881 INFO  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Re-index progress 4000/4170
2012-10-05 10:12:04,939 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: domainkey-signature:b=xnmfpgvl
2012-10-05 10:12:05,492 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3x75puciuaawdidlfe
2012-10-05 10:12:05,495 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:34b1puciuaiwhmhpji
2012-10-05 10:12:05,498 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3bcjpuciualgz4z710
2012-10-05 10:12:05,501 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:31sfpuciuaikejemgf
2012-10-05 10:12:05,503 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:38mbpuciuakechcked
2012-10-05 10:12:05,539 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3glppuciuals272a43
2012-10-05 10:12:05,549 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3xrbpuciuao0qvqysr
2012-10-05 10:12:05,553 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3d7bpuciuaj4zezhba
2012-10-05 10:12:05,556 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3xb1puciuahapupxrq
2012-10-05 10:12:05,564 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3dlppuciuabkqvqysr
2012-10-05 10:12:05,567 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3obppuciuanwzezhba
2012-10-05 10:12:05,570 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3iklpuciuaaschcked
2012-10-05 10:12:05,573 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3jqlpuciuabeiniqkj
2012-10-05 10:12:05,597 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3kqlpuciuabumrmuon
2012-10-05 10:12:05,600 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3y45puciuabgpupxrq
2012-10-05 10:12:05,603 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: dkim-signature:b=p7f3haxcejc18
2012-10-05 10:12:05,607 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: dkim-signature:b=dz1u/mkgv5kvk
2012-10-05 10:12:05,609 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3xo5puciuabmkpksml
2012-10-05 10:12:05,674 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3xgdvuciualesxs0ut
2012-10-05 10:12:05,677 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3vqtvuciuaborwrzts
2012-10-05 10:12:05,680 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3haxvuciuahky3y60z
2012-10-05 10:12:05,689 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: x-mailingid:16784448::mdepnoti
2012-10-05 10:12:05,689 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: domainkey-signature:b=rwa/czy7
2012-10-05 10:12:05,800 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: domainkey-signature:b=kzlnpc3b
2012-10-05 10:12:05,822 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: list-unsubscribe:network.com/c
2012-10-05 10:12:05,822 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: x-sendgrid-eid:rl4q6mtaordmnta
2012-10-05 10:12:05,827 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: dkim-signature:b=putqynjcupscp
2012-10-05 10:12:05,854 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: subject:8?b?rg93bmxvywqgew91ci
2012-10-05 10:12:05,892 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: x-mailingid:16787337::iseriesm
2012-10-05 10:12:05,892 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: domainkey-signature:b=dyfvgux5
2012-10-05 10:12:05,931 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: subject:ascii?b?qnv5ienozwfwie
2012-10-05 10:12:06,015 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: dkim-signature:b=putqynjcupscp
2012-10-05 10:12:06,020 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: domainkey-signature:b=kzlnpc3b
2012-10-05 10:12:06,059 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: x-sendgrid-eid:rl4q6mtaordmnta
2012-10-05 10:12:06,059 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: x-sendgrid-id:gmipbvgfbocak+zh
2012-10-05 10:12:06,059 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: list-unsubscribe:mailto:unsubs
2012-10-05 10:12:06,083 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: list-unsubscribe:network.com/c
2012-10-05 10:12:06,083 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: x-sendgrid-eid:rl4q6mtaordmnta
2012-10-05 10:12:06,088 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3mx5uuciualarwrzts
2012-10-05 10:12:06,103 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: return-path:3ur5uuciuam4lqltnm
2012-10-05 10:12:06,189 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: x-bounce-tracking-info:twlsbgv
2012-10-05 10:12:06,217 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: dkim-signature:b=x4ebctleqwp03
2012-10-05 10:12:06,548 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: dkim-signature:b=i8byirmca0kto
2012-10-05 10:12:06,548 WARN  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Unable to index: domainkey-signature:b=oy58s6d5
2012-10-05 10:12:06,814 INFO  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Batch complete processed=4170,failed=0,elapsed=53338 (78.18 items/sec)
2012-10-05 10:12:06,815 INFO  [ReIndex-0] [name=somebody@somewhere.tld;mid=2;] index - Re-index completed items=4170,failed=0,elapsed=53549 (avg 12 ms/item, 83 items/sec)