Every time the mail client refreshes your incoming mail folder, it s taking server time to read the contents of the folder. Refreshing every 5 minutes rather than more frequently, holds down the overall mail traffic and frees the servers up to process more mail. Each confirmation requested generates another e-mail message. Mail attachments increase mail message size because even simple, short attachments contain your text plus formatting instructions from the software package used to create the attached file. Use of the background stationary option inflates the size of a mail message because it embeds a graphic image.
Larger messages increase processing time per message and slow down overall mail flow.
Additionally, other mail packages often cannot interpret the stationery or graphics, so the receiver cannot open or cannot see your text. The new mail is there but can t be viewed due to the 300-message limitation. When messages are deleted and the folder drops below 300 messages, new incoming messages will again appear. Leaving read messages in New Mail inflates the folder size and slows down refreshing the folder when new mail comes in. Users should adjust their settings to automatically move to Main or another folder.