There are some attachments that will not send if you try to attach them to an email message.
These attachments are:
ade, adp, ani, bas, bat, chm, cmd, com, cpl, crt, dll, exe, hlp, hta, inf, ins, isp, js, jse, lnk, mdb, mde, msc, msi, msp, mst, pcd, pif, reg, scr, sct, shb, shs, vb, vbe, vbs, wri, wsc, wsf, wsh
*Note: An attached .zip file that contains one of the file types listed above, will also fail to send.
In general, you will experience better performance with your email program if you have caching enabled (generally enabled by default). Caching mail makes copies of your mail messages to your local hard drive, which is useful for accessing messages offline, with slow connections, or if often on the move. Without caching no mail will be available without a connection.
If you have a large mailbox (10 GB and over), it may be beneficial to disable caching or cache only for during a certain time period. Please refer to the following recommendations for using caching with your mail client:
To clear nickname cache in Outlook, follow the following steps: