topic Re: Attaching pdfs to transactional emails in APIs & Integrations

Attaching pdfs to transactional emails

THammer — Wed, 07 Dec 2022 09:53:08 GMT

Hi,

We are looking into sending transactional emails from HubSpot, either through SMTP og single-send.

In order to do so, we will need to be able to attach pdfs; both static and dynamic ones. According to this blog post from HubSpot in 2020, "The SMTP API gives you the unique ability to add attachments, including PDFs", but we cannot find any documentation to support this.

My questions are:

(2) is it possible to add any kind of pdf to a transactional email through single-send? I.e. so that we could create a unique pdf per transactional email externally and attach it?

Re: Attaching pdfs to transactional emails

coldrickjack — Wed, 07 Dec 2022 11:40:13 GMT

Hey @THammer,

I am the author of that article, I originally shared it on LinkedIn whilst I was working at HubSpot (no longer working there) and decided to put it up on the developer blog.

It's true that you can add attachments to transactional emails but only if you are using the SMTP API. It doesn't work if you use the Single Send API. As a rule of thumb any emails built within the HubSpot email editor don't support attachments whether they're marketing or transactional. The UI doesn't allow for it.

To answer your questions specifically:

My questions are:

(1) is it possible to attach pdfs to transactional emails? (not just by adding a link to a static file)? If I've understood it correctly, HubSpot's SMTP API works by simply providing the server, so it should be possible to do this when designing the email. - Yes, but only using the SMTP API. With the SMTP API you have full and total control of the email and are simply using HubSpot SMTP as the mechanism to send and track.

(2) is it possible to add any kind of pdf to a transactional email through single-send? I.e. so that we could create a unique pdf per transactional email externally and attach it? No, not as an attachment. The workaround if you are using Single Send API is to generate a link to a PDF file and include it as a custom token in the body of your email. It's not a true attachment in that sense but at least the recipient has a link to the file that is specific to them.

In short if you want to include attachments, it's possible but only with the SMTP API.

Re: Attaching pdfs to transactional emails

HubCon55 — Wed, 11 Jun 2025 14:19:49 GMT

For the Sinlge Send API using a file url stored in hubspot, it looks like you have to use a signed url, which then breaks when sending because UTM tracking. Any way around this? We can't turn off UTM tracking completely.

Re: Attaching pdfs to transactional emails

hkampen — Thu, 05 Feb 2026 11:37:58 GMT

It would be great to have the opportunity to add attachemnets to tansactionals based on e-mail templates.

Another solution would be if I could render an e-mail template by API. Simular to the transactional e-mail api, a new endpount takes the template ID and custom parameters, but returns the rendered e-mail include sender, rendered subject and other parameters.

Re: Attaching pdfs to transactional emails

BérangèreL — Thu, 05 Feb 2026 12:28:14 GMT

Hey @hkampen 👋, I hope that you are well!

Thanks for reaching out to the HubSpot Community!

I’ve noticed a similar idea already present in our Ideas Forum: Attachments for transactional emails.

To contribute, you can upvote the existing idea and share more details about your specific use case in the comments.

And regarding rendering Email Templates via API, I'd love to put you in touch with our Top Experts: Hi @coldrickjack, @Anton and @SteveHTM can you think of a workaround to help @hkampen, please?

Thanks so much and have a wonderful day!
Bérangère

Re: Attaching pdfs to transactional emails

hkampen — Fri, 06 Feb 2026 09:12:40 GMT

Hello @BérangèreL,

I also looked for a Python script that can render the HTML from the fragmented response in the email API but didn't found one.

Our current workaround is to copy the HTML from a email template into our code base where we have to remove tracking features.

Re: Attaching pdfs to transactional emails

BérangèreL — Fri, 06 Feb 2026 12:19:59 GMT

Hey @hkampen, thanks so much for sharing your workaround with the HubSpot Community!

I am sure this will be helpful for many other Members facing the same.

Thanks again and have a lovely weekend!
Bérangère