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Written By
Simran Bhatia -
Approved By
Sonika Rawat -
Updated on
December 9th, 2025 -
Read Time
6 minutes
Best Methods to Efficiently Merge EML Files into One File
Email archives continue to evolve with sharing and migration, or when consolidating old mailboxes, preparing for litigation, or clearing the storage. Scattered EML files in these situations make the workflow hard to manage. Thus, it is necessary to merge multiple EML files to ensure that you get a clean index, simple search, and better portability across all Mac and Windows OS. This guide outlines the effective manual method and a trusted EML Converter to explain how to merge EML files into a single file with ease.
Why Merge Multiple EML Files into One Single File?
Several scenarios demand different users to perform the EML file merge as mentioned below:
- Forensic Team: Merge files to gather evidence sets for a flexible chain of custody.
- Open EML File on macOS: Consolidate EML exports from various devices before importing to Apple Mail or migrating elsewhere.
- Enterprise Teams: Prefer a unified file containing all email messages in one folder for quick transfers.
- Smart Archival: To compress years of archive and backup data into one file for simplified access.
- Data organization: Preserving the data integrity in a portable, readable format, keeping everything organized and manageable.
If you are clear on the above factors, then let’s proceed towards the efficient solutions for the merger.
Optimal Solutions to Merge EML Files
You can easily merge .eml files with the help of manual methods using an EML-supported application. Alternatively, you can download professional software that offers control and automation for straightforward data access in a matter of time.
DIY to Combine EML Files into One File
If you want to merge EML manually, then using the Mozilla Thunderbird application is a good option. This is because it works on Windows and Mac OS, and can save all your EMLs into a single unified MBOX file, accessible across platforms. The steps are:
- First, launch Thunderbird on your PC and log in with your profile.
- Then, create a new folder within the Local Folders section.
- Further, install the ImportExportTools NG extension from Add-ons and Themes.
- Afterward, right-click the new folder within Local Folders.
- Now, choose ImportExportTools NG and opt for Import EML Messages.
- Browse to select all the EML files from your PC and open them in Thunderbird’s new folder.
- Later, right–click on the same new folder again with EML files.
- Next, select ImportExportTools NG again and then click Folder Export (MBOX).
- Select As MBOX File and click on Individual MBOX files.
- Finally, you will receive a single unified MBOX file containing all your EML files.
An Alternative to Merge EML Files for Free
If you are a technical expert and can work with the Command Prompt, then these steps can help you with the merge as well:
- Initially, move all the EML files into a single folder on your PC.
- Then, open Command Prompt (cmd) and navigate to the same folder.
- Lastly, run the command copy *.eml mergedfile.eml to create a single merged EML file.
- For macOS, in the terminal, run the command cat *.eml > mergedfile.eml.
Why the Free Approach is Not Generally Preferred?
The common shortcomings of the manual method are as follows:
- Unsuitable solution for a large number of EML files.
- Often, attachments are not merged correctly.
- Formatting breaks and inconsistent header issues occur.
- Risk of data loss, missing EMLs, and corruption in the process.
- Suitable only for small non-sensitive EML files.
Pro Method to Join EML Files Together
When the manual method falls short, or you are unsure of merging EML files manually, SysInfo EML Converter Tool comes in handy. This excellent software enables you to batch merge EML files into a single consolidated EML, PDF, PST, MBOX, or any other file of your choice. Additionally, it helps remove duplicates, filter data for a specific period, and manage attachments smoothly with no hassle. Moreover, it requires no expertise, preserves all your EML data, and maintains fidelity and structure.
Note: If you are short on time and need to manage large dataset volumes, SysInfo One-Time Service helps complete the entire merger securely, accurately, and with zero loss and errors.
Simple and Quick Steps to Combine EML Files
- Launch the EML File Converter on your OS and click the Next button.
- Then, choose the Select File/Folder option and select the EML files to open. Tap Next.
- Further, from the tree view, preview and select EML folders to merge. Click Next.
- After that, opt for the desired file format from the saving list and apply filters.
- At last, choose a destination to save the merged EML and click Convert to complete the process.
With these steps, all your files are combined as one in no time. If you want to test this out first with a few files to evaluate software performance and functionality. Then, get the Demo Version.
Do You Know?
With demo, you also get to merge upto 50 emails per folder as one at no cost.
Conclusion
When you merge EML files into one file, you get a cleaner structure, easy migration, and a long-term secure data archival option. Manual methods work fine for smaller mailboxes with a few EMLs, but when professionals require precision, scalability, and absolute merge without loss of data. Then, the EML Conversion Software is the best choice. It perfectly aligns with your needs, provides advanced capabilities, and ensures you get the desired result in minimal time.
Frequently Asked Questions
Q1. Can I join EML Files manually without using software?
Ans. Yes, you can merge multiple EML files into one single file using the command prompt or the Mozilla Thunderbird application.
Q2. How long does it take to combine EML Files?
Ans. The time for the merge depends on the method you prefer. With the manual ways, it may take a few hours to a few days if you have multiple files as well. Whereas with the professional tool, it is completed in a matter of time.
Q3. Does merging EML files affecting attachments?
Ans. When you join EML files together for free, the attachments are not merged correctly. But the EML File Converter ensures that either the attachments are not migrated or merged appropriately as per your preference.
Q4. Is there any size limit to merge EML files?
Ans. Manual methods often struggle with large archives, but the smart software supports unlimited EML file merge without size limitations.
Q5. Is there any best tool to merge EML Files?
Ans. The EML Converter Software by SysInfo is among the best tools to merge multiple EML files into one.
About The Author:
Simran Bhatia is a technical content writer engaged in writing clear, concise, and SEO-optimized content. With a background in computer science and a passion for writing, I thrive to deliver complex technical content in simple layman terms.
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