Good night, this command
/tool e-mail send to="destination@gmail.com" subject=([/system identity get name]." backup") file=export.rsc start-tls=yes;
works fine and send the email when I remove the file attachment, but when i try to send the export file the log show stuck in “email: send .”
and the email never arrive to the inbox, this fail in just one router, i have many in the same networl and works fine.
thanks
Check your MTU and check if the firewall settings do not block all ICMP
it’s so strange cause, without the attachment the email goes fine, the same script it’s working in all other aps in the network, same RouterOS version, all it’s the same config.
This is not strange at all when your MTU is too high somewhere and/or you are blocking ICMP “destination unreachable” somewhere.
So go check that.
Make sure you keep Steve Gibson and his advices far from your config!
ok, i understand your advice, but just to clarify to you, this ap is behind a router like other 16 aps, all of them can send the email without problems, there’s nothing blocking ping, in fact, i dont have nothing blocked in my network, so where i must change the mtu and how? also, i dont understand your comment about Steve.. 
thanks
When you think that ICMP is the same as PING then it is not strange that you have problems.
The same appears to be true for many other firewall advisors on internet.
Good luck finding your issue!