What is the MAXIMUM number of email addresses I can send - for a mass customer email?? (~ 2500)
eM Client has no limit, but there will be one from your email provider which varies depending on how you are sending the message.
Take GMail for example:
If all the addresses are in the To, CC or BCC field, there will be a limit of something like 500 recipients per message.
If you use eM Client’s mass mail feature, which sends a separate customized message to each recipient. Gmail personal accounts have a limit of something like 150 messages per day.