| copyright |
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| lastupdated | 2025-12-05 | ||
| keywords | email delivery faq | ||
| subcollection | email-delivery |
{{site.data.keyword.attribute-definition-list}}
{: #email-delivery-faq} {: faq}
Frequently asked questions for {{site.data.keyword.cloud}} Email Delivery for Classic might include questions about delivery options or information about SendGrid. To find all of the FAQs for {{site.data.keyword.cloud_notm}}, see our FAQ library. {: shortdesc}
{: #can-i-use-port25} {: faq}
As of 28 October 2015, {{site.data.keyword.cloud}} no longer allows outbound connections through TCP port 25 (SMTP) on new accounts.
{: #why-is-port25-blocked} {: faq}
By default, the standard SMTP TCP port 25 is blocked due to the large amount of abuse that is targeted at this port. {{site.data.keyword.cloud}} offers a trusted third-party email relay service from {{site.data.keyword.SendGrid}} if you need to send outbound email from their domains or applications.
{: #what-options-send-email} {: faq}
If you need to send email from your servers, you need to use a smart host outside of {{site.data.keyword.cloud}}. A smart host is a host that relays SMTP traffic from an SMTP server, mail client, or any other service or programming language capable of handling SMTP. Servers typically send this type of traffic by using the mail submission TCP ports 465 or 587. You can communicate with 465, 587, or any custom port other than TCP port 25. If you want to use your own email server on a custom port, use the documentation specific to your email service to configure a custom email port.
{: #why-emails-flagged-as-spam} {: faq}
Your emails can be flagged as spam if you don't use authentication with RDNS, DMARC, BIMI, SPF, or DKIM. If your emails don't comply with internet privacy laws, then they might be blocked or flagged as spam. The following are some common privacy laws.
- Controlling the Assault of Non-Solicited Pornography and Marketing (CAN-SPAM)
- Canada Anti-Spam Law (CASL)
- General Data Protection Regulation (GDPR)
- California Consumer Protection Act (CCPA)
{: #why-email-not-being-delivered}
- Your email size might be higher than the threshold restrictions. Failure notices often give more details about size restrictions.
- The recipient server might block your emails because of compliance and regulation reasons. For more information, see Why are my emails flagged as spam?.
{: #why-emails-taking-long-deliver}
Internet traffic congestion and SMTP server configuration issues can cause delivery delays. Contact your email vendor.
{: #why-recipients-not-see-email-but-shows-delivered}
The recipient might have filters set up that move emails into folders other than the inbox. For more information, see SendGrid - Troubleshooting email messages marked "Delivered", But not appearing in inbox{: external}.
{: #offer-smart-host-service} {: faq}
{{site.data.keyword.cloud}} now offers an email delivery service that is powered by {{site.data.keyword.SendGrid}} that allows clients to use a smart host to relay your outbound mail services. This service has many other functions such as generating metrics, tracking email lists, tracking email activity, assisting with newsletters, and authenticating.
{: #why-warm-up-IP-address} {: faq}
Warming up an IP address gradually increases the volume of email that is sent from a dedicated IP address that follows a predetermined schedule. The gradual increase helps establish a good reputation with ISPs as a legitimate email sender.
{: #how-warm-up-ip-address} {: faq}
The proper volume and frequency of your email program depends on your total email volume. But, you need to send enough email at a volume that ISPs can properly determine your reputation. See the following suggestions to help build your reputation.
- Start by sending a welcome message to your hyper-engaged recipients. Then, send the message to your recently engaged recipients.
- If you don't have engagement data, keep in mind that your recent signups are most active right after they sign up to your email list.
For more information, see SendGrid’s Email Guide for IP Warm Up{: external}.
{: #how-get-dedicated-ip-address} {: faq}
If you want a dedicated IP address, send a request to ibm_partner@twilio.com. Make sure that you include the account contact information and your SendGrid account email address.
{: #is-sendgrid-only-choice-email-delivery} {: faq}
No. But, you need to use SendGrid through {{site.data.keyword.cloud}} to have your email service appear on the same {{site.data.keyword.cloud}} invoice.
If you want to use a third-party email delivery product, you need to use a smart host that is outside of {{site.data.keyword.cloud}}. A smart host relays SMTP traffic from an SMTP server, email client, or any other service or programming language that can handle SMTP.
{: #how-use-own-email-server} {: faq}
Contact support to request an exemption to open port 25 so you can host your own email server.
{: #how-get-help-sendgrid} {: faq}
Log in to your SendGrid account and submit a support request. If you can't log in, see How to Contact SendGrid support if you cannot log in to your account{: external}.
{: #where-sendgrid-tos} {: faq}
For the Terms of Service for SendGrid and Twilio, see Twilio Terms of Service{: external}.
{: #where-more-information-sendgrid} {: faq}
For more information about SendGrid, see SendGrid documentation{: external}.