Hello,
The default recommended maximum size for the delivery is 60 KB. However AC does not validate the size so even size is more then 60 KB AC will try to send it.
Having size more then 60 KB can lead the performance issue in delivery sending as your delivery might be too big to be processed quickly it will increase the load on MTA's
As such there is no restriction for having the maximum URL's but If necessary, you can de-activate tracking on a URL, including when the URL of the link is used as a label; this avoids risks of rejection due to phishing. For example, if the www.adobe.com URL is inserted into the message, the content of the hypertext link will be modified (if the URL is tracked) to http://nlt.adobe.net/r/?id=xxxxxx. This means that it could be considered as fraudulent by recipient message clients.
Refer the below link's for Adobe Campaign Delivery best practices and to learn about content guidelines.
Delivery best practices
Managing deliverability
Adobe Campaign Premium and Ultimate (formerly Campaign Managed Services) | Product description
Adobe Campaign Standard | Product description
