Hello. I used an SG e-mail address the other day and never got the e-mail that was sent to the address. So, I tried a test and sent an e-mail myself to that very same SG address. My test e-mail finally did come through -- more than 22 hours later.
Then, another e-mail I was expecting through an SG address never came and it was a very important e-mail. Now I'll have to call the organization and see what they were trying to communicate to me in the e-mail. I've been having problems with my SG address for months but they just keep getting worse and worse.
I hope you're not accepting new sign-ups because this service doesn't seem to be working very well anymore, apparently due to the hardware limitations I've read about elsewhere in these forums.
I'd also respectfully recommend that you replace your phpBB forums with Simple Machines Forums (SMF). SMF is far more robust that phpBB, can be set up to not expose the memberlist to guests or search engines, and it has a very nice CAPTCHA mod that stops the automated signups. Your phpBB board is so spammed in the memberlist and regularly in forum posts that it's just plain unprofessional. I realize your memberlist is set so that it's not accessible when clicking the memberlist link. Nevertheless, it does seem to be getting spammed regularly and that can only serve to clutter up the phpBB database, I would think. SMF does have a phpBB-to-SMF converter that works well for converting phpBB boards to SMF. I've used the converter several times and it has worked well for each board I've converted. Beware of the Visual Confirmation option in phpBB's admin section. It's basically useless. The graphical characters it displays are so basic in form that they are easily scanned and converted to text by bots/programs, as is proven on this web page.
Also, I see that links still don't show as links in posts in this forum, at least not in preview. I have a number of links in this post, but you'd never know it by looking at a preview before posting. So, I made the font color blue and underlined each link manually.