Personalized versus Non-personalized Messages
There are two methods to use to send a message to multiple recipients:
Non-personalized is when a single message is transferred to the server and then the server sends it out to many recipients.
Personalized is when a separate message is sent to each recipient.
Many anti-spam filters will filter out non-personalized messages, and the number of people using such filters is constantly growing, so we strongly suggest using personalized messages whenever possible.
Sending non-personalized messages is faster, and AY Mail by default tries to send non-personalized messages unless it has to send messages one by one. AY Mail is forced to send personalized messages if any one of the following conditions occur:
1. You have used any Macro in the message text or subject line.
2. You selected Direct Sending or send through AY Track.
3. You explicitly requested personalized messages (on the Advanced tab for Professional and Corporate Editions, or on the Message tab for Home Edition).
4. You specified a custom attachment with the Attach Custom File dialog.
If your list is not large, it is better to send personalized messages. However, with large lists or if your message is big (usually because it contains graphics or attached files) sending personalized messages may be very time-consuming, as it is much slower. There is really no reason to use non-personalized messages except for the speed. Also, keep in mind that the gain in speed is just for the time required to transfer the message to the server. It will take some time until server sends all the messages to their recipients.