Article ID: 2799505 - View products that this article applies to.
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Assume that in an Office 365 environment, you try to send or receive files or attachments in Lync through Lync Online. In this situation, you may experience the following issues:
  • You can't send files to contacts.
  • You can't receive files from contacts.
  • You can't upload file attachments in Lync online meetings.
  • When you send files to contacts, you receive an error message.
  • You can’t send pictures directly in an Instant Messaging (IM) conversation.


For Lync Online users

If you receive an error message when you send or receive files, make sure that the file type being transferred isn’t one of those that is listed in the "More Information" section. 

For Lync Online administrators

If a user doesn’t see the option to transfer files, verify that file transfer capabilities are enabled for that user. For more information, go to the following Microsoft website: 
Configure file transfer, audio-video, and recording
Firewalled networks must meet the network requirements for Lync Online. For more information about Lync Online network requirements, go to the following Microsoft Knowledge Base article:
2409256 You can't connect to Lync Online, or certain features don't work, because an on-premises firewall blocks the connection


Generally, if the menu option to send a file isn't available, this means that the administrator has disabled file transfer capabilities for that user.

If your attempts to upload attachments to a conference or to send files to a contact generate an error message, this means either that the contact that you’re sending the attachment to doesn’t have permission to receive files or that the file type is blocked.

In Lync Online, certain files types are blocked by the Intelligent Instant Message Filter (IIMF) application. IIMF helps protect Lync Online users against the most common forms of viruses without degrading the user experience.

Transferring files to Skype contacts isn't supported.

By default, Lync Online is configured to prevent users from sending files through IM that have the following file name extensions:
.ade, .adp, .app, .asp, .bas, .bat, .cer, .chm, .cmd, .com, .cpl, .crt, .csh, .exe, .fxp, .grp, .hlp, .hta, .inf, .ins, .isp, .its, .js, .jse, .ksh, .lnk, .mad, .maf, .mag, .mam, .maq, .mar, .mas, .mat, .mau, .mav, .maw, .mda, .mdb, .mde, .mdt, .mdw, .mdz, .msc, .msi, .msp, .mst, .ocx, .ops, .pcd, .pif, .pl, .pnp, .prf, .prg, .pst, .reg, .scf, .scr, .sct, .shb, .shs, .tmp, .url, .vb, .vbe, .vbs, .vsd, .vsmacros, .vss, .vst, .vsw, .ws, .wsc, .wsf, .wsh

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

Still need help? Go to the Office 365 Community website.


Article ID: 2799505 - Last Review: June 25, 2014 - Revision: 6.0
Applies to
  • Microsoft Lync Online
o365 o365e o365p o365a o365022013 kb3rdparty KB2799505

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