One of those mails which locks up Claws-Mail

I've just had one email lock up Claws-Mail. 
It's a text email.
I've run Claws-Mail with the debug flag and collected the output, and
viewed the offending mail with 'less'.

I really am not sure why this mail has stopped all Claws activity, and
left me with a white screen.

I am willing to share the full data with a developer if required.
This is the last 20 lines of the debug txt
$ tail -n 20 /tmp/claws.txt 
summaryview.c:3110:Sorting summary done.
summaryview.c:3117:TIMING summary_sort : 0s004ms
summaryview.c:3373:TIMING summary_set_ctree_from_list bold_unread:
0s000ms summaryview.c:3378:TIMING summary_set_ctree_from_list : 0s009ms
summaryview.c:1682:
summaryview.c:1687:called inc_unlock (lock count 0)
summaryview.c:1688:TIMING summary_show : 0s040ms
folder.c:2603:Total cache memory usage: 1521009
folderview.c:2392:TIMING folderview_selected : 0s764ms
folderview.c:2268:newly selected 0x2381000, opened 0x2381000
folderview.c:2272:TIMING folderview_selected : 0s000ms
imap.c:1584:trying to fetch cached
/home/liz/.claws-mail/imapcache/mail.*******.net/liz/INBOX/1452218
imap.c:1594:message 1452218 has been already fully cached.
procheader.c:174:generic_get_one_field: empty line message/rfc822
(offset:0 length:2221 encoding: 6) text/plain (offset:1300 length:921
encoding: 0) procheader.c:174:generic_get_one_field: empty line
procheader.c:197:generic_get_one_field: empty line
textview.c:692:TIMING textview_add_part : 0s002ms
textview.c:1165:Viewing text content of type: plain (length: 921)

I'll not try to remove the email yet, in case further tests are advised.

A second text email from the same sender was read with no difficulties.

Liz