Maybe a duplicate of bug 63388; however, bug 95140 does not freeze and provides error messages.

Can you test with the latest, there were a lot of changes: http://dev-builds.libreoffice.org/daily/master/Win-x86@62-merge-TDF/current/

Set to NEEDINFO.
Change back to UNCONFIRMED, if the problem persists. Change to RESOLVED WORKSFORME, if the problem went away.

(In reply to Buovjaga from comment #2)
Unfortunately, Email Test Setting failed in:
Version: 5.2.0.0.alpha0+
Build ID: 157469896ef56720f33676222b95e81c04ab5c72
CPU Threads: 2; OS Version: Windows 6.2; UI Render: default; 
TinderBox: Win-x86@62-merge-TDF, Branch:MASTER, Time: 2016-04-06_20:10:15

Perhaps having automatic configuration of email settings may help? For example, this is implemented in Thunderbird.

LibreOfficeDev could not connect to the outgoing mail server. Check your system's settings and the settings in LibreOfficeDev. Check the server name, the port and the secure connections settings
--
<class 'poplib.error_proto'>: -ERR EOF, traceback follows
  C:\Program Files (x86)\LibreOfficeDev 5\program\python-core-3.3.0\lib\poplib.py:121 in function _getline() [if not line: raise error_proto('-ERR EOF')]
  C:\Program Files (x86)\LibreOfficeDev 5\program\python-core-3.3.0\lib\poplib.py:137 in function _getresp() [resp, o = self._getline()]
  C:\Program Files (x86)\LibreOfficeDev 5\program\python-core-3.3.0\lib\poplib.py:93 in function __init__() [self.welcome = self._getresp()]
  C:\Program Files (x86)\LibreOfficeDev 5\program\mailmerge.py:405 in function connect() [self.server = poplib.POP3(server, port, timeout=tout)]

----
Output from:
Version: 5.2.0.0.alpha0+
Build ID: 157469896ef56720f33676222b95e81c04ab5c72
CPU Threads: 2; OS Version: Windows 6.2; UI Render: default; 
TinderBox: Win-x86@62-merge-TDF, Branch:MASTER, Time: 2016-04-06_20:10:15

TESTING with
LO 5.2.0.0.alpha1+
OS Version: Mac OS X 10.10.5
Build: 2016-05-11_01:01:27

(In reply to Óvári from comment #0)
> 2. Enter:
>    a) Your name                     : <name>

The Name field doesn't seem to affect my test results.

>    b) E-mail address                : <email_address>@gmail.com
>    c) Server name                   : smtp.gmail.com

smtp.googlemail.com and smtp.gmail.com appear to both work (or at least TEST) equally well for me.

>    d) Port                          : 587
>    e) Use secure connection (SSL)   : Selected
> 3. Click "Server Authentication"
>    a) The outgoing mail server 
>       (SMTP) require authentication : Selected
>    b) The outgoing mail server uses 
>       the same authentication as the 
>       incoming mail server server   : Selected
>    c) Server name                   : pop.gmail.com
>    d) Port                          : 995
>    e) Type                          : POP3
>    f) User name                     : <email_address>@gmail.com
>    g) Password                      : <password>

I tried this configuration option with SMTP, and also got 'Failed' messages:

>    c) Server name                   : imap.gmail.com
>    d) Port                          : 993
>    e) Type                          : IMAP

> 
> Any help to enable emailing within LibreOffice to work with a gmail.com
> email address would be appreciated. Thank you

Possible Fix:
Try selecting the 2nd option: "The outgoing mail server (SMTP) needs separate authentication" and fill in your email address and password. That change to the config works for me.

Ovari: I'll mark this as NEEDINFO for now. If my suggested config works for you, please change the Status to RESOLVED WORKSFORME, otherwise please change back to UNCONFIRMED and let us know if you received a different error message. Thanks!

(In reply to Robinson Tryon (qubit) from comment #5)
> I tried this configuration option with SMTP, and also got 'Failed' messages:

Oops! That should read 'IMAP', not 'SMTP'.

Thank you Robinson Tryon (qubit) for your comments. I have tried to make LibreOffice email merge work, but unfortunately have been unsuccessful.

In the meantime a solution that works with Thunderbird:
  http://getthunderbird.com/
is Mail Merge by Alexander Bergmann:
  https://addons.mozilla.org/thunderbird/addon/mail-merge/

It would be nice if email merge worked with LibreOffice, hence:
Status: NEEDINFO → UNCONFIRMED

Thank you

Mike, i know that you love mail merge. Any opinions about this bug?

In the default LibreOffice installation, please include "Advanced Outgoing Server Settings":
* Connection Timeout
* Authentication method (Without, Login/password, OAuth2)
* Connection security (unsecure, SSL, TLS).

This setting can then be added to:
Menu Bar → Tools → Options → LibreOffice Writer → Mail Merge E-mail
The "Mail Merge Advanced Outgoing Server Settings.png" shows an image mock with the inclusion of the the gMailOOo extension.

There may also be a link to these setting in the:
Menu Bar → Tools → Mail Merge Wizard…

What do you think?

Thank you

(In reply to prrvchr from bug 63388 comment 17)
> I make an extension gMailOOo:
> 
> https://github.com/prrvchr/gMailOOo?files=1
> 
> Who implements ssl and tls as well as OAuth2.
> Uno api uno seems obsolete and requires an upgrade.

Created attachment 145791 [details]
Mail Merge Advanced Outgoing Server Settings

Hi Óvári,
Could you please try to reproduce it with the latest version of LibreOffice
from https://www.libreoffice.org/download/libreoffice-fresh/ ?
I have set the bug's status to 'NEEDINFO'. Please change it back to
'UNCONFIRMED' if the bug is still present in the latest version.

(In reply to Xisco Faulí from comment #16)
Not sure how to use LibreOffice to do this anymore as the menus/dialogs/etc have changed. Thank you

Hi all,

gMailOOo is now obsolete, (no more development), if you want to use OAuth2 protocol you must now use: OAuth2OOo

See my comment: https://bugs.documentfoundation.org/show_bug.cgi?id=63388