webform_mail gives warning: array_merge() [function.array-merge]: Argument #2 is not an array

Have the same problem, but it did not get rid of the error messages. Thanks for the tip

Hi guys, could you tell me what (if any) modules you're using related to e-mails? Are you doing any custom theming of your e-mails? Can this be reproduced on a clean install? Currently I'm not seeing this issue and these are the only reports of it.

I am using mimemail with only the default mail.css altering the width of the email

Still haven't been able to reproduce this issue. Please reopen if you can provide steps to reproduce from a clean Drupal install, including all version numbers of installed modules.

We are experiencing the same issue, and we are not using any additional modules relating to emails.
We are using Webform 6.x-3.18

I have attached a patch for the fix in the original issue.

@ben.denham: Please provide instructions on reproducing this problem from a clean install of Webform. As far as I can tell, there isn't a problem here. The only way I could see this problem happening would be if theme_webform_email_headers() was overridden in your theme and you returned an empty string (instead of an empty array).

I get this error in 7.x-4.0-beta1.
I have added the following to template.php:

function fusion_core_webform_mail_headers_312($variables) {
  $headers = array(
    'Content-Type'  => 'text/html; charset=UTF-8; format=flowed; delsp=yes',
    'X-Mailer' => 'Drupal Webform (PHP/' . phpversion() . ')',
  );
  return $headers;
}

The error is:
Warning: array_merge() [function.array-merge]: Argument #2 is not an array i webform_mail() (linje 1954 af /home/mysite/public_html/sites/all/modules/webform/webform.module).
Warning: Invalid argument supplied for foreach() i DefaultMailSystem->mail() (linje 54 af /home/mysite/public_html/modules/system/system.mail.inc).
Warning: array_merge() [function.array-merge]: Argument #2 is not an array i webform_mail() (linje 1954 af /home/mysite/public_html/sites/all/modules/webform/webform.module).
Warning: Invalid argument supplied for foreach() i DefaultMailSystem->mail() (linje 54 af /home/mysite/public_html/modules/system/system.mail.inc).

Applying the "fix" in #0 removes the error.
I haven't any mail-related modules installed.

Followup on #7:
Outlook reports the following headers:
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed; delsp=yes
Content-Transfer-Encoding: 8Bit
X-Mailer: Drupal

Text/plain?

Closed for lack of activity