Checked SMTP server trace, it shows the sender has no permission to send the email:
2016-01-20 04:36:15 132.245.160.34 OutboundConnectionCommand SMTPSVC1 PMT-NPS01 - 6684723 MAIL - FROM:+SIZE=3336 0 0 4 0 6344 SMTP - - - -
2016-01-20 04:36:15 132.245.160.34 OutboundConnectionResponse SMTPSVC1 PMT-NPS01 - 6684723 - - 250+2.1.0+Sender+OK 0 0 19 0 6469 SMTP - - - -
2016-01-20 04:36:15 132.245.160.34 OutboundConnectionCommand SMTPSVC1 PMT-NPS01 - 6684723 RCPT - TO: 0 0 4 0 6469 SMTP - - - -
2016-01-20 04:36:15 132.245.160.34 OutboundConnectionResponse SMTPSVC1 PMT-NPS01 - 6684723 - - 250+2.1.5+Recipient+OK 0 0 22 0 6500 SMTP - - - -
2016-01-20 04:36:15 132.245.160.34 OutboundConnectionCommand SMTPSVC1 PMT-NPS01 - 6684723 BDAT - 3336+LAST 0 0 4 0 6500 SMTP - - - -
2016-01-20 04:36:18 10.10.16.46 WFOPRITH SMTPSVC1 PMT-NPS01 10.10.30.22 0 HELO - +WFOPRITH 250 0 45 13 0 SMTP - - - -
2016-01-20 04:36:18 10.10.16.46 WFOPRITH SMTPSVC1 PMT-NPS01 10.10.30.22 0 QUIT - WFOPRITH 240 16 45 13 0 SMTP - - - -
2016-01-20 04:36:21 132.245.160.34 OutboundConnectionResponse SMTPSVC1 PMT-NPS01 - 6684723 - - 550+5.7.60+SMTP;+Client+does+not+have+permissions+to+send+as+this+sender 0 0 72 0 11657 SMTP - - - -
**Updated** Customer was attempting to email contacts but the browser was freezing with no errors pop ups, and no emails being sent. Below is an example from event viewer showing an office component failing.
Faulting application name: jp2launcher.exe, version: 11.71.2.15, time stamp: 0x5679fc95
Faulting module name: mso30win32client.dll, version: 16.0.4266.1001, time stamp: 0x55ba12f1
Exception code: 0xc0000005
Fault offset: 0x0007e4e7
Faulting process id: 0x1ff8
Faulting application start time: 0x01d26dd70921d32e
Faulting application path: C:\Program Files (x86)\Java\jre1.8.0_71\bin\jp2launcher.exe
Faulting module path: C:\Program Files (x86)\Common Files\Microsoft Shared\Office16\mso30win32client.dll
Report Id: 7695bf66-d9ca-11e6-9753-80000b0c7677