I’m not sure what you mean by 15 days to update the servers… The servers are stable and operating normally. There’s no need to update them except for normal system updating.
The issue is between our system and Gmail or other mail service providers. Outside of utilizing best practices, the secret sauce to get into Gmail inboxes and the email inboxes of other service providers in not disclosed publicly. These providers hold their filtering rules close to their chest. However, IP address reputation is very important, and a factor which is known to be important. The IP address of our mail server is the single biggest change I can point to as a possible cause within the last month.
If you are referring to the period of time needed to rebuild the reputation of our mail server’s IP address, this is unknown and may differ from service provider to service provider. Ultimately, the main thing we can control to get our emails to you is to adhere to email best practices and to not be emailing things people regard as spam. We hope to do this and be able to have our email delivered 100% of the time to peoples inboxes.
Hope this helps!
Abraham