[5.1] Fix attachment handling in libraries Mail class

[LadySolveig]

Pull Request for Issue # .

Summary of Changes

It is currently not possible to attach a single attachment with the disposition 'inline' to a mail via the Mail library class.

Above all, this means that it is also not possible to send an image as an inline attachment via the Mail class and then simply refer to it via cid.

This means that in the e-mails that are sent when they are received on different clients, the download of the images must first be approved by the user before they are visible.

The changes in the Mail class address issues with attachment handling. Specifically:

• Ensured the addAttachment method includes the $disposition parameter in all cases.
• Simplified the logic for adding attachments by removing redundant checks.
• Added a check to ensure $name is an array before comparing its count with $path.

Testing Instructions

Set the option Mail Format -> HTML in Global Configuration -> Mail Templates

Add the following lines of code (only!) for testing into the file 'libraries/src/Mail/MailTemplate.php' line 277

$logo = Path::clean(JPATH_ROOT . '/images/banners/white.png');
# Attach the logo as inline attachement
$this->mailer->addAttachment($logo, basename($logo), 'base64', mime_content_type($logo), 'inline');
// We need only the cid for attached logo file inline
$htmlBody .= '<img src="cid:' . htmlspecialchars(basename($logo), ENT_QUOTES) . '" alt="Test inline attachment" style="max-width:80%;height:auto;border:none;text-decoration:none;color:#ffffff;">';

Send a test mail under Global Configuration -> Server tab at the bottom of the page using the Send Test Mail button

Actual result BEFORE applying this Pull Request

Attachment is inserted but not as an inline attachment and thus the assignment to the image fails.

Expected result AFTER applying this Pull Request

Attachment is inserted as an inline attachment and thus the assignment to the image works.

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[brianteeman]

I have tested this item ✅ successfully on 574d39d

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43828.}

[bembelimen]

I have tested this item ✅ successfully on 574d39d

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43828.}

[Quy]

RTC

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43828.}

[bembelimen]

Thx