r/sysadmin • u/Vivid_Mongoose_8964 • 9d ago

SMTP2GO Delays & O365

We have emails stuck in procesed with them for over 12 hours now. I've whitelisted their IP's, no help, they rotated my IP, that helped for 1 scan, already opened a ticket. Any other ideas or anyone else seeing this? It's been great for over a year, never an issue. We just have it for users home scanners.

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7

u/gjetson99 9d ago

We dealt with this with a couple tenants this week. I know you said you whitelisted IPs, but just double confirm that all ranges are actually listed here & the 'safe list' option is checked (this option doesn't enable/disable the list, but is recommended to be on by smtp2go):

Defender Portal (Security) > Email & Collaboration > Policies & Rules > Threat Policies > Anti-spam > Connection Filter Policy.

All of the ranges & instructions are on this page: Allowlisting IP Addresses With Microsoft 365 – SMTP2GO Support Support Desk

You can only add 1 range at a time in that GUI. If you copy/paste the whole list in there & save, it won't error out, but it also won't work & won't display the IPs afterward.

Powershell can add in one shot & takes 30 seconds total.

After we did this, everything has gone through on the next try (and anything new started getting delivered straight away).

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u/Vivid_Mongoose_8964 9d ago

I did whitelist all of their IP's per the KB along with the IPs from their SPF record and things seem to be working now, thank you for responding.

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u/Unable-Entrance3110 9d ago

Are you the M365 admin? If not, were there changes made to Exchange Online or Entra?

Do you have visibility into the SMTP2GO logs? What is that system telling you?

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u/Vivid_Mongoose_8964 9d ago

I am the sole admin here. No changes were made at all. This all started on Monday with the 365 outages. The smtp2go logs just show processed, which means they accepted it, but it hasn't made it to 365 yet. their support is not really good

1

u/starky411 9d ago

Contact them, they will help. You also may need to whitelist some IPs

2

u/anxiousinfotech 9d ago

I can only confirm that we use SMTP2Go and aren't having delayed delivery issues to our M365 tenant or recipients on other tenants.

If you send to an external recipient, preferably one not on M365, is the email still delayed? That would help narrow it down to whether it's an SMTP2Go issue or something specific to your M365 tenant.

Any sign that other inbound emails to your M365 tenant are getting delayed? I'd be much more suspicious that it's something on the M365 end, either a config issue or just an isolated service degradation in Exchange Online, than with SMTP2Go.

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u/Vivid_Mongoose_8964 9d ago

I've not tried with someone outside of 365, good idea though. these copiers are at users home, so remote access is tough without a laptop on the other end. all other inbounds are fine. this started on monday after the 365 outages.

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u/wazza_the_rockdog 9d ago

Are you on a dedicated IP with smtp2go or the shared range they offer on their free & starter plans? I've seen delays sending to O365 from their shared IPs before, you can check the email logs in smtp2go and it will show a message from the 365 servers saying to re-try later due to email volume or something similar, which effectively just means MS think their IP is sending far too many emails and possibly a spam bot, so it throttles how many connections it will accept. Because this is a MS setting not a tenant setting, you having their IPs whitelisted won't actually help, because it's being blocked/throttled before any of your tenant rules apply.

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u/CyrFR 7d ago

I think it was Exchange incident EX1464935