What Is Port 25 and why is it being blocked?
To help control the amount of spam and viruses that originate from your ISP (like Optimum Online or Earthlink, etc.) your Internet Service Provider may start to implement outbound Port 25 (SMPT) filtering. Filtering Port 25 is a common spam control measure used by Internet Service Providers and the advantages far outweigh the disadvantages when it comes to the war on spam. However, these efforts will not necessarily protect yourself from being flooded with spam. To protect your email account from spam, we suggest you take a look at our Email Defense Service.
