Bounce are of two types hard and soft boucne and 1 % bounce in email campaign is not a problem.
Hard Boucne
A hard bounce indicates a permanent reason an email cannot be delivered. Bounced email addresses are removed automatically from the list and placed in the Blacklist portion of your list. Blacklist subscribers will be excluded from future campaign sends to this list. While there are many reasons an email address may hard bounce, these are some common reasons this could happen.
*Recipient email address does not exist.
*Domain name does not exist.
*Recipient email server has completely blocked delivery.
Soft Bounce
Soft bounces typically indicate a temporary delivery issue to an address and are handled differently than hard bounces. When an email address soft bounces, it will immediately display as a soft bounce in the campaign report.
While there are many reasons an email address may soft bounce, these are some common reasons this could happen.
*Mailbox is full (over quota).
*Recipient email server is down or offline.
*Email message is too large.
Please note 5 attempts for Soft bounce is done by our system in the period of three days.