Using gmail smtp for notifications fails

Question

I have set up notifications with smtp.gmail.com as DNS host on the advanced tab 
 Port 587 
 TLS activated 
 Authentication activated 
 my Gmail address with password but notification does not work, this is part of my log 
 2016:03:03-12:51:00 4844 exim-out[31196]: 2016-03-03 12:51:00 End queue run: pid=31196 
 2016:03:03-12:51:07 4844 exim-out[30646]: 2016-03-03 12:51:07 1abRT8-0007Nt-0r deadmail.fw-notify.net [93.189.156.232]:25 Connection timed out 
 2016:03:03-12:51:07 4844 exim-out[30645]: 2016-03-03 12:51:07 1abRT8-0007Nt-0r == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (110): Connection timed out 
 2016:03:03-12:51:07 4844 exim-out[31250]: 2016-03-03 12:51:07 1aax1G-0002Wp-6r == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[31252]: 2016-03-03 12:51:07 1aaaXi-0002Rz-F7 == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[31254]: 2016-03-03 12:51:07 1abRCK-0006n1-1x == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[31256]: 2016-03-03 12:51:07 1aax1G-0002Wp-6s == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[31258]: 2016-03-03 12:51:07 1aaMPQ-0002sW-4O == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[31260]: 2016-03-03 12:51:07 1aaMNA-0002nt-4v == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[31262]: 2016-03-03 12:51:07 1abRUb-0007R1-0T == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[31264]: 2016-03-03 12:51:07 1aaaXi-0002Rz-F6 == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[31266]: 2016-03-03 12:51:07 1aaMNA-0002nt-4w == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:51:07 4844 exim-out[30640]: 2016-03-03 12:51:07 End queue run: pid=30640 
 2016:03:03-12:52:00 4844 exim-out[31307]: 2016-03-03 12:52:00 Start queue run: pid=31307 
 2016:03:03-12:52:00 4844 exim-out[31309]: 2016-03-03 12:52:00 1abQkN-0005qn-1Y == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31311]: 2016-03-03 12:52:00 1aaaXi-0002Rz-F6 == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31313]: 2016-03-03 12:52:00 1aax1G-0002Wp-6r == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31315]: 2016-03-03 12:52:00 1aaMNA-0002nt-4v == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31317]: 2016-03-03 12:52:00 1aaMPQ-0002sW-4O == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31319]: 2016-03-03 12:52:00 1aaaXi-0002Rz-F7 == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31321]: 2016-03-03 12:52:00 1abRCK-0006n1-1x == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31323]: 2016-03-03 12:52:00 1aax1G-0002Wp-6s == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31325]: 2016-03-03 12:52:00 1abRUb-0007R1-0T == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31327]: 2016-03-03 12:52:00 1abRT8-0007Nt-0r == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31329]: 2016-03-03 12:52:00 1ab5Z6-0003Ru-5p == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31331]: 2016-03-03 12:52:00 1aaMNA-0002nt-4w == xxx@gmail.com R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:52:00 4844 exim-out[31307]: 2016-03-03 12:52:00 End queue run: pid=31307 
 2016:03:03-12:53:00 4844 exim-out[31389]: 2016-03-03 12:53:00 Start queue run: pid=31389 
 2016:03:03-12:53:00 4844 exim-out[31391]: 2016-03-03 12:53:00 1abQkN-0005qn-1Y == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:53:00 4844 exim-out[31393]: 2016-03-03 12:53:00 1abRT8-0007Nt-0r == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:53:00 4844 exim-out[31395]: 2016-03-03 12:53:00 1abRUb-0007R1-0T == do-not-reply@fw-notify.net R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host 
 2016:03:03-12:53:50 4844 smtpd[4882]: MASTER[4882]: (Re-)loading configuration from Confd 
 2016:03:03-12:53:50 4844 smtpd[4882]: MASTER[4882]: QR globally disabled, status one set to 'disabled' 
 2016:03:03-12:53:50 4844 smtpd[4882]: MASTER[4882]: QR globally disabled, status two set to 'disabled' 
 2016:03:03-12:53:50 4844 exim-in[5138]: 2016-03-03 12:53:50 pid 5138: SIGHUP received: re-exec daemon 
 2016:03:03-12:53:50 4844 exim-in[5138]: 2016-03-03 12:53:50 exim 4.82_1-5b7a7c0-XX daemon started: pid=5138, no queue runs, listening for SMTP on port 25 (IPv4) port 587 (IPv4) and for SMTPS on port 465 (IPv4) 
 2016:03:03-12:54:00 4844 exim-out[31535]: 2016-03-03 12:54:00 Start queue run: pid=31535

stegman · Accepted Answer

Changing the hostname will stop notifications if the hostname consists of only numbers. 
 I changed it back to 4844 and notifications stopped. 
 Reboot UTM did not help. 
 I restarted the postfix and got an error about invalid hostname with all numbers. 
 I changed it back to all letters and rebooted the UTM (because i was told that restarting the postfix to much could cause other problems) 
 and the notifications started working again. 
 
 This to inform that the use of only numbers (perhaps no numbers are allowed at all?) is not a valid hostname configuration. 
 
 p.s. actually i did not rebooted the UTM but turned if off and on again. 
 I am not sure a restart will do the same as off - on 
 Today i was connected with VPN and rebooted the UTM and i could login again without reconnecting the VPN so i think it has not completely rebooted but only restarted some daemons/services?