Linc, here's the log. I was able to add two photos without freezing the mail, then when I added an address in the "to" field, it froze. Thanks.
12/19/2014 8:33:06.200 PM sharingd[286]: 20:33:06.200 : Starting Handoff advertising
12/19/2014 8:33:08.435 PM sharingd[286]: 20:33:08.435 : Starting Handoff advertising
12/19/2014 8:33:17.408 PM sharingd[286]: 20:33:17.407 : Starting Handoff advertising
12/19/2014 8:33:25.272 PM sharingd[286]: 20:33:25.272 : Starting Handoff advertising
12/19/2014 8:33:34.392 PM sharingd[286]: 20:33:34.391 : Starting Handoff advertising
12/19/2014 8:33:36.393 PM sharingd[286]: 20:33:36.392 : Stopping Handoff advertising
12/19/2014 8:33:40.067 PM sharingd[286]: 20:33:40.067 : Starting Handoff advertising
12/19/2014 8:33:41.033 PM sharingd[286]: 20:33:41.032 : Starting Handoff advertising
12/19/2014 8:33:44.320 PM sharingd[286]: 20:33:44.319 : Starting Handoff advertising
12/19/2014 8:33:46.192 PM sharingd[286]: 20:33:46.192 : Starting Handoff advertising
12/19/2014 8:33:55.673 PM sharingd[286]: 20:33:55.673 : Starting Handoff advertising
12/19/2014 8:34:05.100 PM sharingd[286]: 20:34:05.099 : Starting Handoff advertising
12/19/2014 8:34:14.515 PM sharingd[286]: 20:34:14.514 : Starting Handoff advertising
12/19/2014 8:34:24.008 PM sharingd[286]: 20:34:24.008 : Starting Handoff advertising
12/19/2014 8:34:26.324 PM sharingd[286]: 20:34:26.324 : Starting Handoff advertising
12/19/2014 8:34:28.329 PM sharingd[286]: 20:34:28.329 : Stopping Handoff advertising
12/19/2014 8:34:28.670 PM sharingd[286]: 20:34:28.670 : Starting Handoff advertising
12/19/2014 8:34:29.082 PM Mail[459]: *** -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[1]
12/19/2014 8:34:29.087 PM Mail[459]: (
0 CoreFoundation 0x00007fff9138564c __exceptionPreprocess + 172
1 libobjc.A.dylib 0x00007fff9411b6de objc_exception_throw + 43
2 CoreFoundation 0x00007fff912729bf -[__NSPlaceholderDictionary initWithObjects:forKeys:count:] + 383
3 CoreFoundation 0x00007fff912886ab +[NSDictionary dictionaryWithObjects:forKeys:count:] + 59
4 Mail 0x00000001083b7064 Mail + 524388
5 Mail 0x00000001083b5121 Mail + 516385
6 Mail 0x00000001083b4ac2 Mail + 514754
7 Mail 0x00000001083b1bc2 Mail + 502722
8 CoreFoundation 0x00007fff9125e33c __invoking___ + 140
9 CoreFoundation 0x00007fff9125e192 -[NSInvocation invoke] + 290
10 MailCore 0x00007fff943b11d4 -[MCThrowingInvocationOperation main] + 48
11 MailCore 0x00007fff94342fae -[MCMainThreadInvocationOperation main] + 55
12 Foundation 0x00007fff8be56f4c __NSThreadPerformPerform + 293
13 CoreFoundation 0x00007fff912a3661 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
14 CoreFoundation 0x00007fff912957ed __CFRunLoopDoSources0 + 269
15 CoreFoundation 0x00007fff91294e1f __CFRunLoopRun + 927
16 CoreFoundation 0x00007fff91294838 CFRunLoopRunSpecific + 296
17 HIToolbox 0x00007fff8ba1b43f RunCurrentEventLoopInMode + 235
18 HIToolbox 0x00007fff8ba1b1ba ReceiveNextEventCommon + 431
19 HIToolbox 0x00007fff8ba1affb _BlockUntilNextEventMatchingListInModeWithFilter + 71
20 AppKit 0x00007fff8d3316d1 _DPSNextEvent + 964
21 AppKit 0x00007fff8d330e80 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 194
22 AppKit 0x00007fff8d324e23 -[NSApplication run] + 594
23 AppKit 0x00007fff8d3102d4 NSApplicationMain + 1832
24 libdyld.dylib 0x00007fff8ec6d5c9 start + 1
)
12/19/2014 8:34:38.148 PM sharingd[286]: 20:34:38.148 : Starting Handoff advertising
12/19/2014 8:34:46.013 PM sharingd[286]: 20:34:46.012 : Starting Handoff advertising
12/19/2014 8:34:48.014 PM sharingd[286]: 20:34:48.013 : Stopping Handoff advertising