No connection to server

[GTP95]

Hello.
Your library is really useful but I ran into a problem. Using the TestMail example I'm able to send an email but if I use the same settings in my code it fails. Sometimes it fails silently even if the debug mode is set to 3 (I can tell it failed because I added some serial output), some others it just outputs "No connection to server!" followed by the server's address and port. I'm sure that the ESP8266 is connected to the WiFi network because it hosts a webpage that I can reach. Here's my code, the only real difference I found between it and the example is that I call the mail functions inside the "loop" part of the sketch instead of the "setup" part but this shouldn't matter, right? Did I do something wrong?

NOTES: In the code below I put the debug mode to 0 because the level 3 wasn't providing any additional output. Sensitive informations are replaced whit an asterisk. There are some comments left from another project I modified, I left those to give you exactly the same sketch I'm compiling, even if they shouldn't affect the result.

Here's a pastebin link to my code: https://pastebin.com/8rj6Vvcf
EDIT: removed code and added pastebin link